DOC: Remove makePanel from docs (#25609)
- [x] closes #25609
- [ ] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

As described in #25609, I removed the tm.makePanel() calls from the docs, along with some of the surrounding sections (a few "Deprecate Panel" sections).  I did not replace these calls with an equivalent manual creation of a Panel.

If desired, I could create a panel manually in the docs with something like this:

```
cols = ['Item' + c for c in string.ascii_uppercase[:K - 1]]	
data = {c: tm.makeTimeDataFrame() for c in cols}	
p = Panel.fromDict(data)
```

but this PR is currently as requested in the issue with the sections removed.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=h1) Report
> Merging [#25612](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/0d893d080da96ebed42302032fe337d77ce5d9eb?src=pr&el=desc) will **decrease** coverage by `49.55%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25612/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=tree)

```diff
@@             Coverage Diff             @@
##           master   #25612       +/-   ##
===========================================
- Coverage   91.26%   41.71%   -49.56%     
===========================================
  Files         173      173               
  Lines       52968    52968               
===========================================
- Hits        48339    22093    -26246     
- Misses       4629    30875    +26246
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `?` | |
| #single | `41.71% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/formats/latex.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvbGF0ZXgucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/core/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY2F0ZWdvcmljYWwucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/sas/sas\_constants.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfY29uc3RhbnRzLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/plotting.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvcGxvdHRpbmcucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29udmVydGVyLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/formats/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvaHRtbC5weQ==) | `0% <0%> (-99.36%)` | :arrow_down: |
| [pandas/core/groupby/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9jYXRlZ29yaWNhbC5weQ==) | `0% <0%> (-95.46%)` | :arrow_down: |
| [pandas/io/sas/sas7bdat.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXM3YmRhdC5weQ==) | `0% <0%> (-91.17%)` | :arrow_down: |
| [pandas/io/sas/sas\_xport.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfeHBvcnQucHk=) | `0% <0%> (-90.15%)` | :arrow_down: |
| [pandas/core/tools/numeric.py](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvbnVtZXJpYy5weQ==) | `10.44% <0%> (-89.56%)` | :arrow_down: |
| ... and [130 more](https://codecov.io/gh/pandas-dev/pandas/pull/25612/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25612?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/25612?src=pr&el=footer). Last update [0d893d0...63627ff](https://codecov.io/gh/pandas-dev/pandas/pull/25612?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/25612?src=pr&el=h1) Report
> Merging [#25612](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/0d893d080da96ebed42302032fe337d77ce5d9eb?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/25612/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25612   +/-   ##
=======================================
  Coverage   91.26%   91.26%           
=======================================
  Files         173      173           
  Lines       52968    52968           
=======================================
  Hits        48339    48339           
  Misses       4629     4629
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.83% <ø> (ø)` | :arrow_up: |
| #single | `41.71% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25612?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/25612?src=pr&el=footer). Last update [0d893d0...14dd01a](https://codecov.io/gh/pandas-dev/pandas/pull/25612?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 I've converted all the old whatsnew entries to code-blocks using what was in the stable docs.  I did not do that for the 'Deprecate Panel' section in dsintro, if you would like me to do it there as well just let me know. I've fixed the linting errors.  I did have to add a `# noqa E999` in `v0.13.1.rst` as flake8-rst was unable to parse that code-block. thanks @ArtificialQualia 

