Improve README.rst

[pilosus]

I've conducted a small survey amongst my colleagues about what they would like to be improved in pydantic as a github project. Many of them said that an almost blank README.rst make them think the package is not really alive. I think it's a good point. As many developers use GitHub as a kind of social network, checking for projects people they follow like or star, we need a quick introduction to what pydantic is. I know it's already in the documentation. But saving people a few mouse clicks may make a difference.

README.rst should not copy or extend a great documentation we already have. Instead it should tell GitHub users (i.e. developers) the most essential things about pydantic in a concise manner.
I'd suggest the following structure:

• Intro (what's pydantic)
• Installation (pip)
• A Simple Example (a first example from the docs)
• Contributing (link to contributing section in the docs)
• Links
  • Documentation
  • License
  • Releases in the CheeseShop
  • Source code (GitHub link)
  • Issue tracker (GitHub Issues)
  • Test status
  • Test coverage

[pilosus]

@samuelcolvin actually I already have a draft version. It's compiled from the pydantic docs to follow the structure from above. If you think that having a richer README would help, I can submit a PR so that it's easier to make a final version of README

[samuelcolvin]

Sounds good, but:

• Shouldn't be too long. Eg. Less than ~800px high
• Keep using rst so it can also be used for pypi.
• Make the documentation link very prominent incase people think "that's all there is" when looking at the readme.

[samuelcolvin]

Also no need for github links in the readme.

Perhaps we should include download numbers from pypi/bigquery.

Conda-forge link should be added too.