[Epic] Better documentation

[shin-]

• Making use of Sphinx autodoc for API docs #454 Making use of Sphinx autodoc for API docs
• Document possible exceptions #499 Document possible exceptions
• Clean up documentation #821 Clean up documentation
• how to use the 'log-drive' #964 Hostconfig doc should provide the available list of ulimit names #943 Documentation for ulimits and logging configuration is absent / lacking
• Support ipv4_address and ipv6_address in create_endpoint_config #1083 (comment) Network documentation / thematic separation for API docs.

Main takeaways:

• API docs are poorly formatted and difficult to navigate.
• Some users find it valuable to have the documentation closer to the code itself.
• More information could be given about the behavior of our methods (exceptions raised, etc.)
• User guides in addition to functional documentation could prove useful.

[dnephin]

If I could add one more point, I think it would be awesome to have a link from the docker-py docs to the official API for the endpoint as well.

[shin-]

I didn't think of that, but you're right. Noting this down!

[bfirsh]

I've added some check boxes to see how we're doing here! I think the only things left are:

• Really comprehensive exception docs. This is much improved in A new user-focused API #1186, which at least documents what internal exceptions are raised, but I think documenting external exceptions is far too large of a job. We could handle on a case-by-case basis based on what bugs we get, etc.
• ulimits docs. Don't think this is done, yet.
• Some users guides are in A new user-focused API #1186, the rest will be in Better API and SDKs documentation docs#210

[huogerac]

Hello, I'd like to know if I did something wrong or miss something due to make my PR reviewed.
Cheers