Convert docstrings into Markdown and publish API docs

[sanand0]

Is your feature request related to a problem? Please describe. https://learn.gramener.com/gramex/ documents the Gramex libraries, but is not part of the guide, not well written, and is hard to maintain, partly because it's in ReST not Markdown

Describe the solution you'd like

1. Move this as an integral part of the guide
2. Convert docstrings from ReST into Markdown

Additional context

Some notes on how to use Sphinx with Markdown

• https://stackoverflow.com/q/2471804/100904
• https://github.com/readthedocs/recommonmark
• https://myst-parser.readthedocs.io/en/latest/

@bhatsandeep @bkamapantula @jaidevd -- your thoughts please?

[bkamapantula]

+1

happy to contribute