chore: generate docs with sphinx

[KingDarBoja]

References #89

So far so good, to generate the docs just run sphinx-build -b html -EW docs docs/_build/html and navigate to docs/_build/index.html and that's it!

However, the index is not listing anything whereas the modindex isn't being generated.

[coveralls]

Coverage remained the same at 100.0% when pulling d2ae379 on KingDarBoja:sphinx-docs into 8fc378d on graphql-python:master.

[leszekhanusz]

Good start!

Todo:

• fix import order
• fix manifest errors
• we will need to sanitize all the help comments in the docs so that the methods are correctly explained
• is it possible to hide private methods in the docs ? (starting with an underscore)

[KingDarBoja]

• is it possible to hide private methods in the docs ? (starting with an underscore)

Yes, in this case would be manually importing every function/class per module instead of dumping all as I did. In fact, that was my original approach but as I wasn't sure how many stuff was going to be displayed on the docs, I went for the generic solution.

EDIT Feel free to check again, I hide all private members as requested. 🚀

[KingDarBoja]

If the structure is okay, then would be great to start moving the readme into a subsection called "usage" like graphql-core docs does.

[leszekhanusz]

Note: I created the gql project on readthedocs.io and I think the webhook is in place so if I understand correctly, once we merge this PR it should be visible on gql.readthedocs.io

[leszekhanusz]

First I still need to correct the references now...

[leszekhanusz]

Note: I improved the class references but I removed the DSL module reference for now (no time and it will probably change...)

[KingDarBoja]

Outstanding documentation, everything seems to be well documented. I will provide a separate section for DSL in the short term.