Documentation (docstrings & how-tos)

[yunruse]

Now that v1.0 is on the horizon, it would be great to document the API that exists.

• [ ] Find suitable docstring-to-docs generator
• [ ] Write out all the docstrings
• [ ] See if the docs can't be put into GH Wiki
• [ ] Write a guide for common use cases

[yunruse]

duplicate of #13?