DOC: Add dateutil to intersphinx #24437
- [x] closes #24437 
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=h1) Report
> Merging [#24443](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/8b4b38fd7995cb59b0595f2d06cb4b984b5886a9?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24443/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #24443      +/-   ##
==========================================
+ Coverage    92.3%   92.31%   +<.01%     
==========================================
  Files         163      163              
  Lines       51977    51977              
==========================================
+ Hits        47979    47980       +1     
+ Misses       3998     3997       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.71% <ø> (ø)` | :arrow_up: |
| #single | `42.99% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/24443/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `87.84% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24443?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/24443?src=pr&el=footer). Last update [8b4b38f...91d13fe](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=h1) Report
> Merging [#24443](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/8b4b38fd7995cb59b0595f2d06cb4b984b5886a9?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/24443/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24443   +/-   ##
=======================================
  Coverage    92.3%    92.3%           
=======================================
  Files         163      163           
  Lines       51977    51977           
=======================================
  Hits        47979    47979           
  Misses       3998     3998
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.71% <ø> (ø)` | :arrow_up: |
| #single | `42.99% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24443?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/24443?src=pr&el=footer). Last update [8b4b38f...ae6aa27](https://codecov.io/gh/pandas-dev/pandas/pull/24443?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 did you generate the documentation and checked if the link to the dateutil documentation works?

out of curiosity? what order are the intersphinx modules following now? I generated the documentation and the dateutil link worked okay for example in the pandas.tseries.offsets.DateOffset doc you initially described.

The order is now alphabetically listed to make it slightly more legible for reading through the list as it grows and changes. Ah, whoops! I reordered the listing and then added dateutil. Fixed now. thanks @benjaminr  No probs @jreback 