Remove defined-in and constants

[skatkov]

I'm still trying to nail down a proper structure for markdown output.

In this release, I'm trying to remove:

• "defined in" section -- there are multiple issues with getting this section right, so let's drop it for now.
• constants section -- table view doesn't work and I generally don't consider those critical enough to take so much space. It would also add, that there are too much constant shown )might be inherited).
• swap place "class methods" section and "instant methods" section