feat(docs): Create sphinx docs using setuptools

[GMishx]

How to generate the documentation using setuptools

1. Build atarashi (or install sphinx using pip install sphinx m2r)

   python3 setup.py build

2. Refresh source .rst files

   sphinx-apidoc -Pe -o ./docs/source/ ./atarashi

3. Check for new modules files (if any) and add :private-members: under your new .. automodule::.

4. Generate the docs

   python3 setup.py build_sphinx

5. Check python3 setup.py build_sphinx --help for more.

[amanjain97]

@GMishx I think we should not add .rst files to the repository. If anyone wants to contribute to the docs, he/ she can submit the patch generated according to "How to generate Sphinx documentation" which can be reviewed by the admin/ maintainers.

[GMishx]

I added the .rst files to add the :private-members: to every module. So if anyone creates documentation, they can get the private functions in the docs. I could not find any other way to add it other than adding it manually to every file. Can be done programmatically though.