Resolution docstring
- [ ] closes #xxxx
- [ ] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

```
################################################################################
################### Docstring (pandas.Timedelta.resolution)  ###################
################################################################################

Return a string representing the lowest (i.e. smallest) time resolution.

Each timedelta has a defined resolution that represents the lowest OR
most granular level of precision. Each level of resolution is
represented by a short string as defined below:

============ ============
Resolution   Return value
============ ============
Days         ``'D'``
Hours        ``'H'``
Minutes      ``'T'``
Seconds      ``'S'``
Milliseconds ``'L'``
Microseconds ``'U'``
Nanoseconds  ``'N'``
============ ============

Returns
-------
str
    Time resolution.

Examples
--------
**Using string input**

>>> td = pd.Timedelta('1 days 2 min 3 us 42 ns')
>>> td.resolution
'N'

>>> td = pd.Timedelta('1 days 2 min 3 us')
>>> td.resolution
'U'

>>> td = pd.Timedelta('2 min 3 s')
>>> td.resolution
'S'

**Using integer input**

>>> td = pd.Timedelta(36, unit='us')
>>> td.resolution
'U'

################################################################################
################################## Validation ##################################
################################################################################

Errors found:
	See Also section not found
```
@WillAyd 

I am new to contributing to `pandas`.

* What specific changes do you want me to make? I have been looking at this thread and clicking through to various links and I am not sure what changes I should make.

Are your requested changes to that I should tweak the PR to use the three commits marked above with the red `x`s?

IF yes... I would request some guidance on the matter of the Return values...

When I look at the documentation guide produced for the recent Pandas Documentation Sprints, this guidance is present on how to handle single and multiple return values:
```
**With a single return value**
Returns
-------
float
    Random number generated.

**With multiple return values**
Returns
-------
length : int
    Length of the returned string.
letters : str
    String of random letters.
```

Lastly... 
* I see that ci/circleci failed. When I visited the details, the failure does not appear to be anything related to my change (maybe I am missing something)? Any guidance you can offer is greatly appreciated.



 Not sure what happened to my comment so probably an error on my end, but I was just asking why you had the table and the information directly below it as bullet points. It's the same information (?) so if it's duplicated I would just stick with the table and delete the bullets

Took a quick glance at the CI failures and they are LINT related to your change, so you will want to read through them and fix. The steps to reproduce are below:

https://pandas.pydata.org/pandas-docs/stable/contributing.html#python-pep8

That said, if you have run that locally you probably aren't seeing any errors because the diff in that command is only run against "*.py" files and not "*.pyx" which you've modified (most users only modify the former). If feeling ambitious that could be another change to update the docs to make sure that that rule covers both `.py` and `.pyx` files.

Hope that helps but if you get stuck let me know
 Thanks. This helps.
For some reason, I thought I deleted bullets. Sigh. Will do so.
I will go back and rerun the linter checks against the .pyx

 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=h1) Report
> Merging [#21122](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/5cb5880d8f1647e303ba52487dc867db838fd6e0?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/21122/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #21122   +/-   ##
=======================================
  Coverage   91.95%   91.95%           
=======================================
  Files         160      160           
  Lines       49858    49858           
=======================================
  Hits        45845    45845           
  Misses       4013     4013
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.33% <ø> (ø)` | :arrow_up: |
| #single | `42.08% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=footer). Last update [5cb5880...ce7c795](https://codecov.io/gh/pandas-dev/pandas/pull/21122?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Fixed the linting problems.
Removed the bulleted items in deference to using the table.

Hope this works!

```
################################################################################
################### Docstring (pandas.Timedelta.resolution)  ###################
################################################################################

Return a string representing the lowest (i.e. smallest) time resolution.

Each timedelta has a defined resolution that represents the lowest OR
most granular level of precision. Each level of resolution is
represented by a short string as defined below:

============ ============
Resolution   Return value
============ ============
Days         ``'D'``
Hours        ``'H'``
Minutes      ``'T'``
Seconds      ``'S'``
Milliseconds ``'L'``
Microseconds ``'U'``
Nanoseconds  ``'N'``
============ ============

Returns
-------
str
    Time resolution.

Examples
--------
**Using string input**

>>> td = pd.Timedelta('1 days 2 min 3 us 42 ns')
>>> td.resolution
'N'

>>> td = pd.Timedelta('1 days 2 min 3 us')
>>> td.resolution
'U'

>>> td = pd.Timedelta('2 min 3 s')
>>> td.resolution
'S'

**Using integer input**

>>> td = pd.Timedelta(36, unit='us')
>>> td.resolution
'U'

################################################################################
################################## Validation ##################################
################################################################################
``` Removed the backticks. Let me know if we need any additional changes.
This is a good learning experience. I have PRs for `Timedelta.delta` and `Timedelta.asm8` in the wings and this is hopefully setting the stage so those will go more smoothly.


```################################################################################
################### Docstring (pandas.Timedelta.resolution)  ###################
################################################################################

Return a string representing the lowest (i.e. smallest) time
resolution.

Each timedelta has a defined resolution that represents the lowest OR
most granular level of precision. Each level of resolution is
represented by a short string as defined below:

============ ============
Resolution   Return value
============ ============
Days         'D'
Hours        'H'
Minutes      'T'
Seconds      'S'
Milliseconds 'L'
Microseconds 'U'
Nanoseconds  'N'
============ ============

Returns
-------
str
    Time resolution.

Examples
--------
**Using string input**

>>> td = pd.Timedelta('1 days 2 min 3 us 42 ns')
>>> td.resolution
'N'

>>> td = pd.Timedelta('1 days 2 min 3 us')
>>> td.resolution
'U'

>>> td = pd.Timedelta('2 min 3 s')
>>> td.resolution
'S'

**Using integer input**

>>> td = pd.Timedelta(36, unit='us')
>>> td.resolution
'U'

################################################################################
################################## Validation ##################################
################################################################################

Errors found:
	See Also section not found
``` can you update for comments I will update the PR. can you update @jreback not deliberately ignoring this. will get this done, so this open item can be cleared off the books. Attempted to resolve the comments above.

```
################################################################################
################### Docstring (pandas.Timedelta.resolution)  ###################
################################################################################

Return a string representing the lowest timedelta resolution.

Each timedelta has a defined resolution that represents the lowest OR
most granular level of precision. Each level of resolution is
represented by a short string as defined below:

Resolution:     Return value

* Days:         'D'
* Hours:        'H'
* Minutes:      'T'
* Seconds:      'S'
* Milliseconds: 'L'
* Microseconds: 'U'
* Nanoseconds:  'N'

Returns
-------
str
    Timedelta resolution.

Examples
--------
>>> td = pd.Timedelta('1 days 2 min 3 us 42 ns')
>>> td.resolution
'N'

>>> td = pd.Timedelta('1 days 2 min 3 us')
>>> td.resolution
'U'

>>> td = pd.Timedelta('2 min 3 s')
>>> td.resolution
'S'

>>> td = pd.Timedelta(36, unit='us')
>>> td.resolution
'U'

################################################################################
################################## Validation ##################################
################################################################################

Errors found:
	See Also section not found
``` I tried to look in the Travis CI logs and I am not sure what exactly caused the Travis build to fail. Can someone advise?  @chalmerlowe There is a linting error:

`pandas/_libs/tslibs/timedeltas.pyx:837:4: W291 trailing whitespace`

After that fix, LGTM @mroeschke can you push that fix? thanks @chalmerlowe and @mroeschke for the fixup!