Formalize documentation requirements for modules.

[bcpeinhardt]

We should have a set of expectations around field descriptions / general documentation for modules and add those expectations to the CONTRIBUTING.md.
At the same time we should update all modules to match the standard.

[azraa006]

Can u please assign this issue to me

[matifali]

This is complete and is documented in

1. https://github.com/coder/registry/blob/main/CONTRIBUTING.md
2. https://coder.com/docs/about/contributing/modules

Additionally we also have CI in place to validate the requirements. There are more to come to further enforce this. See #406

@DevelopmentCats feel free to reopen of you want to further optimize this.