Improve contributing guidelines #269

The current contributing guidelines describes 3 steps that are quite minimal. We should add additional steps, and maybe we should create a separate contributing.md for better github integration https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/setting-guidelines-for-repository-contributors.

I think the following steps should be atleast added:

• Class pydoc with usage example with the addition of a new container/module
• Integrate module with sphinx