DOC: Remove various warnings from doc build
This gets a handful, though it hasn't addressed https://github.com/pandas-dev/pandas/pull/16050 yet.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=h1) Report
> Merging [#16206](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/f1549668c84b481a67547bb46261d1394c8dd3e7?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/16206/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #16206   +/-   ##
=======================================
  Coverage   90.89%   90.89%           
=======================================
  Files         162      162           
  Lines       50884    50884           
=======================================
  Hits        46250    46250           
  Misses       4634     4634
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.67% <ø> (ø)` | :arrow_up: |
| #single | `40.31% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/formats/style.py](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvc3R5bGUucHk=) | `95.89% <ø> (ø)` | :arrow_up: |
| [pandas/core/indexes/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9pbnRlcnZhbC5weQ==) | `92.58% <ø> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16206?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/16206?src=pr&el=footer). Last update [f154966...71a4655](https://codecov.io/gh/pandas-dev/pandas/pull/16206?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Ah maybe not. I don't know why that gave a warning, meant to revert that change. I'll look more closely in a bit

> On May 2, 2017, at 17:55, codecov[bot] <notifications@github.com> wrote:
> 
> Codecov Report
> 
> Merging #16206 into master will not change coverage.
> The diff coverage is n/a.
> 
> 
> 
> @@           Coverage Diff           @@
> ##           master   #16206   +/-   ##
> =======================================
>   Coverage   90.86%   90.86%           
> =======================================
>   Files         162      162           
>   Lines       50867    50867           
> =======================================
>   Hits        46222    46222           
>   Misses       4645     4645
> Flag	Coverage Δ	
> #multiple	88.65% <ø> (ø)	⬆️
> #single	40.31% <ø> (ø)	⬆️
> Impacted Files	Coverage Δ	
> pandas/core/indexes/interval.py	92.58% <ø> (ø)	⬆️
> pandas/io/formats/style.py	95.89% <ø> (ø)	⬆️
> Continue to review full report at Codecov.
> 
> Legend - Click here to learn more
> Δ = absolute <relative> (impact), ø = not affected, ? = missing data
> Powered by Codecov. Last update 39cc1d0...b64eb54. Read the comment docs.
> 
> —
> You are receiving this because you authored the thread.
> Reply to this email directly, view it on GitHub, or mute the thread.
> 
