* Create CONTRIBUTING.md

* Direct questions to slack channel
Co-authored-by: Brigit Murtaugh <brigit.murtaugh@microsoft.com>

* Use "dev containers" and "Features"

Apparently devcontainers is two words, and apparently features is a proper noun? I guess 🤷‍♂️

* Prettier formatting

I used https://prettier.io/playground/ since I was editing in the GitHub web editor

* Clarify to "only accept improvements and bug fixes"
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>

* Be more explicit about custom features
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>

* Add link to CLI test docs

* Add semver step in guide

* More specificity in link text

https://github.com/devcontainers/features/pull/488#discussion_r1137819187

* Add CONTRIBUTING.md link in readme

---------
Co-authored-by: Brigit Murtaugh <brigit.murtaugh@microsoft.com>
Co-authored-by: Samruddhi Khandale <samruddhikhandale@github.com>