DOC: Fix PEP-8 issues in computation.rst and comparison_*.rst
 - Fix PEP-8 issues in comparison_*.rst
 - Fix PEP-8 issues in computation.rst

Both unrelated. 

CircleCi: Hypothesis test timed out.
```
=================================== FAILURES ===================================
___________________________ test_tick_add_sub[Micro] ___________________________

cls = <class 'pandas.tseries.offsets.Micro'>

    @pytest.mark.parametrize('cls', tick_classes)
>   @example(n=2, m=3)
    @example(n=800, m=300)
    @example(n=1000, m=5)
    @given(n=st.integers(-999, 999), m=st.integers(-999, 999))
    def test_tick_add_sub(cls, n, m):

pandas/tests/tseries/offsets/test_ticks.py:41: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/opt/conda/envs/pandas-dev/lib/python3.6/site-packages/hypothesis/core.py:552: in execute
    ) % (test.__name__, text_repr[0],))
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <hypothesis.core.StateForActualGivenExecution object at 0x7f7503574c50>
message = 'Hypothesis test_tick_add_sub(cls=Micro, n=-138, m=721) produces unreliable results: Falsified on the first call but did not on a subsequent one'

    def __flaky(self, message):
        if len(self.falsifying_examples) <= 1:
>           raise Flaky(message)
E           hypothesis.errors.Flaky: Hypothesis test_tick_add_sub(cls=Micro, n=-138, m=721) produces unreliable results: Falsified on the first call but did not on a subsequent one

/opt/conda/envs/pandas-dev/lib/python3.6/site-packages/hypothesis/core.py:727: Flaky
---------------------------------- Hypothesis ----------------------------------
Falsifying example: test_tick_add_sub(cls=Micro, n=-138, m=721)
Unreliable test timings! On an initial run, this test took 1058.10ms, which exceeded the deadline of 500.00ms, but on a subsequent run it took 0.08 ms, which did not. If you expect this sort of variability in your test timings, consider turning deadlines off for this test by setting deadline=None.
```

Azure: Downloading unsuccessful.
```2018-11-29T22:55:51.8189886Z Exception calling "DownloadFile" with "2" argument(s): "An exception occurred during a WebClient request."
2018-11-29T22:55:51.8190144Z At D:\a\_temp\44684352-d085-41e0-85fc-7478797d5ded.ps1:3 char:1
2018-11-29T22:55:51.8190207Z + $wc.Downloadfile("https://download.microsoft.com/download/7/9/6/796EF ...
2018-11-29T22:55:51.8190284Z + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2018-11-29T22:55:51.8190343Z     + CategoryInfo          : NotSpecified: (:) [], ParentContainsErrorRecordException
2018-11-29T22:55:51.8191084Z     + FullyQualifiedErrorId : WebException
```
 do you mind merging master and pushing, so the CI reruns then? # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24002?src=pr&el=h1) Report
> Merging [#24002](https://codecov.io/gh/pandas-dev/pandas/pull/24002?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b45eb265dd88648fb02ebb0fdcfb168364ab664e?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/24002/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24002?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24002   +/-   ##
=======================================
  Coverage   42.46%   42.46%           
=======================================
  Files         161      161           
  Lines       51557    51557           
=======================================
  Hits        21892    21892           
  Misses      29665    29665
```

| Flag | Coverage Δ | |
|---|---|---|
| #single | `42.46% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24002?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/24002?src=pr&el=footer). Last update [b45eb26...4c09acf](https://codecov.io/gh/pandas-dev/pandas/pull/24002?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @FHaase 