Cleaning up analysis.__ini__ and hole2 docs

[IAlibay]

As discussed in this thread: https://github.com/MDAnalysis/mdanalysis/pull/2778#discussion_r443195698 the analysis.__init__ docstring doesn't seem to be used anywhere and is somewhat superseded by analysis_modules.rst, thoughts on what to do with this text?

Furthermore, linked to that same PR, it seems that there is no page specifically for analysis.hole2, with the docstring instead being in analysis.hole2.hole. Should we be moving the core of the hole2.hole docstring to hole2.__init__ instead?

[orbeckst]

I often use help(module) or module? and then it's nice if a short, comprehensible doc string appears. If we don't use the doc string in the generated docs then I would suggest to cut down analysis.__init__ to something brief (and possibly include a link to the online docs).

All the classes and functions that are important for a user show up under analysis.hole2 so I'd expect the docs to reflect it broadly. I.e., have the general docs appear for hole2 there, so I would move the general docs from hole2.hole to hole2.__init__ and have the classes/functions remain in hole2.hole. I have lately played around with sphinx.autosummary and one could put a summary of classes into hole2.

[manishsaini6421]

@orbeckst Sir , i have fixed this issue. can you review it please.

[IAlibay]

@manishsaini6421 both @lilyminium and I have commented on https://github.com/MDAnalysis/mdanalysis/pull/3579, those comments will need to be addressed before we consider reviewing.

[lilyminium]

Closed by #3579