Upgrade styler to better handle lists
# What does this PR do?

This PR upgrades the doc styling script to automatically add new lines before lists. This makes the script more robust as it will avoid reformatting those lists and make them appear properly once sphinx has done its thing.

In passing a few badly formatted docstrings/doc pages are fixed, just waiting for some input from @patrickvonplaten for the problems in LED/Longformer.

Fixes #9408


I suppose I need to stick to the common bullet format, as it couldn't handle this `\d\) ` style of bullets. Leading to this rewrite:
```
-1) Optimizer State Partitioning (stage 1)
-2) Add Gradient Partitioning (stage 2)
+1) Optimizer State Partitioning (stage 1) 2) Add Gradient Partitioning (stage 2)
```
This is not a problem - will fix the style.<|||||>We also need a new line injector for bulleted lists in .rst checker pretty please.

 In .rst I had:

```
Miscellaneous notes:
- DeepSpeed works with the PyTorch Trainer but not TF Trainer.
- While DeepSpeed has a pip installable PyPI package, 
```
the style wrapper broke the bullets and made them into one paragraph/line.
```
Miscellaneous notes: - DeepSpeed works with the PyTorch Trainer but not TF Trainer. - While DeepSpeed has a pip installable PyPI package, 
```

same problem as with docstring - it's missing a new line again. Could we do the same fix for .rst to inject a new line before bullets if an unwary writer forgot to add one? 

Thank you!

<|||||>Mmm, the patch should be applied to the rst files too (can't link to the diff but it's line 384 of the last file in the diff shown by GitHub).<|||||>I re-based just in case, and no, it still doesn't insert the line. Here is the exact para:
```
Miscellaneous notes:
* DeepSpeed works with the PyTorch Trainer but not TF Trainer.
* While DeepSpeed has a pip installable PyPI package, it is highly recommended that it be `installed from source
  <https://github.com/microsoft/deepspeed#installation>`__ to best match your hardware and also to enable features like
  1-bit Adam, which aren't available in the pypi distribution.
```<|||||>Indeed, I made some stupid mistake, #9488 should fix this.