Python: parse documentation for Python keywords

[isabelizimm]

When looking up keywords such as def or class, the restructured text is not parsed.

[seeM]

It looks like there isn't actually much reStructuredText syntax here. For example, here's what it looks like if we do parse it:

I also tried with pandoc and the result isn't too different.

Given that, I think we can leave it as is for now. If we really want to improve the way it's rendered, one way might be to patch all of the topic pages (defined in the pydoc_data.topics.topics dict) with our own versions rewritten in rST.

[isabelizimm]

I think keeping the indentation of my screenshot is a bit more readable, so I would be in favor of not parsing it for now. Agreed, we can rewrite them in rst at a later point.