Add docs for contributing

[epicfaace]

Reasons for making this change

Add docs for contributing on a separate page, and also explain the development / deployment process for the new multi-package setup.

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests
  • I've updated docs if needed
• I'm adding a new feature
  • I've updated the playground with an example use of the feature

[epicfaace]

@juliankigwana @Saulzi @chanceaclark let me know if this is clearer or if the docs I've added might need more clarification?

[Saulzi]

Yes definitely clarifies things, I will give this workflow a go now

[Saulzi]

unfortunately this did not work on #1610

[Saulzi]

All good

[Saulzi]

Perhaps this should be done when the user pulls the package rather than an additional step otherwise this works for me 👍

[Saulzi]

unfortunately this did not work on #1610

this did after install on bottom level and setting back index.js to be import Form, { withTheme } from "@rjsf/core"; in packages/playground on my branch

[epicfaace]

Would it be simpler, rather than having each package have its own playground start scripts, to just have each package build their files (as @chanceaclark 's PR in #1606 does)? Then, in order to run the playground, one would just need to npm link whichever package they are working on, then run the playground from the packages/playground directory.

This thought came up because I was trying to add the playground to material-ui but realized that doing so would require a lot of overhead for each new package we add.