Docs for contributing code

[MichaelMarien]

Added documentation for getting started with local development and contributing code to DoWhy.
Fixes #528

Open topics I propose to take up later in different PR's:

• potential issue with notebook execution and testing as this happens in a different virtual environment (base) which might not contain all needed dependencies.
• add instructions for creating documentation locally (bash scripts are already provided, should be easy).

Topics not touched due to unclarity on my side

• linting (flake8) and formatting (black, isort): lots of warnings as the current code base is not fully compliant, do we aim so for new contributions and move towards a fully compliant code base? Should any suggestion or requirement towards contributors be included? EDIT: just saw Add formatting check to CI #601 - I'll make a new PR to add formatting instructions later

Signed-off-by: Michael Marien [email protected]

[amit-sharma]

This looks great. Thanks @MichaelMarien . I've added some initial comments.

[darthtrevino]

A couple of comments, but otherwise LGTM

[MichaelMarien]

I believe I fixed all open requests, let me know if something is still missing.

[amit-sharma]

The edits looks great. Approving.

Overall, this is a fantastic resource for developers. Thank you @MichaelMarien for adding this.

[amit-sharma]

@all-contributors please add @MichaelMarien for doc.

[allcontributors]

@amit-sharma

I've put up a pull request to add @MichaelMarien! 🎉