message: docs(contributing): Add section in contributing to state MR conventions
  Adds a merge request guidelines section
  Switch to squashed, conventional-style commits for MRs
  Specify preference for rebase over merges
  Link to a resource explaining a recommended git flow
diff: -## Find an issue
  +# Contributor Guidelines
  +
  +## Merge Requests
  +
  +Contributors MUST:
  +
  +- Discuss a feature before implementing it
  +- Include unit and integration tests applicable to the changes and fixes you made
  +- Format your code with `cargo +nightly fmt` before creating a commit
  +- Follow [Conventional Commit] guidelines, so that our changelogs are useful
  +- Squash commits, such that each commit clearly does a specific thing, either locally or using gitlab's custom checkbox.
  +- [Adhere to a git workflow using rebase](https://medium.com/singlestone/a-git-workflow-using-rebase-1b1210de83e5)
  +- Rebase upon the master branch, rather than merging it
  +- [Allow us to make commits on your merge request](https://docs.gitlab.com/ee/user/project/merge_requests/allow_collaboration.html)
  +
  +Contributors MUST NOT:
  +
  +- Have merge commits in their merge requests
  +- Make breaking changes without clearly documenting them in the commit
  +- Have commits which do not adhere to [Conventional Commit] guidelines
  +
  +Contributors SHOULD NOT:
  +
  +- Worry about code style, because `cargo fmt` renders this a non-issue
  +
  +[conventional commit]: https://www.conventionalcommits.org/en/v1.0.0-beta.4/
  +
  +## Finding an issue
  First, find an area to work on within the shell or one of it's related projects.
  This may be:
  