readme not clear on purpose or contribution guidelines

[mprorock]

The readme attached to this repo needs some enhancement to make it easier for new developers to approach the API or those wishing to implement the API in a conformant manner.

There are also no contribution guidelines, etc.

Happy to jump in and take a stab at getting some better docs pulled together on this.

[OR13]

Agreed, we had previously resolved to follow an api style guide.

https://restfulapi.net/

I suggest we add some guidance related to that to the top level readme, and explictly address the controller vs collection style endpoints.

[mprorock]

editors: @peacekeeper @msporny @mavarley @OR13 @mkhraisha
can we add the tag: plugfest-march-2021 to this issue

[msporny]

We discussed this in 2022-01-18, @mprorock provided an update where contribution guidelines were documented via PRs that were merged. Also discussed in issue #97 ... group decided to close this issue as a result.