docs: Update CONTRIBUTING.md to give more context (rackerlabs#522)

CONTRIBUTING.md

@@ -1,14 +1,41 @@
 # Contributing
 
+Welcome!  Thank you for wanting to contribute to Genestack!
+
 When contributing to this repository, please first discuss the change you wish to make via issue,
 email, or any other method with the owners of this repository before making a change. However, if
-you see a problem, fix it.
+you see a problem, feel free to fix it.
+
+## Branching
+
+1. Please fork the repository and create a feature/modification branch.  GitHub
+   [makes this easy](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-and-deleting-branches-within-your-repository).
+2. **Test your changes!** -- If you are making changes to the general Genestack repo, do a clean build
+   from scratch.  If you are changing the docs, then rebuild the docs from scratch and lint your
+   Markdown.  (You can use [this](https://gist.github.com/OpenStackKen/846a045ecfe74f1895d5c93cbb2fe801)
+   to simply check for trailing spaces, or you can go full [Markdown Lint](https://github.com/igorshubovych/markdownlint-cli)
+   on it.
+3. Once your branch builds, make sure you're caught-up to main and rebase if necessary.
+
+## Commits
+
+1. We are trying to use [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) for our
+   repository.  This allows us to have an easy way to tell what each commit is trying to achieve, and
+   will speed reviews.
+2. This [cheatsheet](https://gist.github.com/OpenStackKen/5c99d4a5d69085718a0d3d0bfc6b2231) can be
+   helpful to keep around to use to make commits easy.
+3. Keep your changes atomic.  Smaller commits centered around specific changes are easier to merge than
+   big "jumbo" commits that touch things in many places.
+4. Commits need to be [signed](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits)
+    and will need to show up as [verified](https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification) in GitHub.
 
 ## Pull Request Process
 
-1. Ensure any install or build dependencies are removed before the end of the layer when doing a 
+1. Ensure any install or build dependencies are removed before the end of the layer when doing a
    build.
-2. Update the README.md / Wiki with details of changes to the interface, this includes new environment 
+2. Make sure you haven't added any extraneous files to the repository (secrets, .DS_Store, etc.) and
+   double-check .gitignore if you have a new type of change.
+4. Update the README.md / Wiki with details of changes to the interface, this includes new environment
    variables, exposed ports, useful file locations and container parameters.
-3. You may merge the Pull Request in once you have the sign-off of two other developers, or if you 
+5. You may merge the Pull Request in once you have the sign-off of two other developers, or if you
    do not have permission to do that, you may request the second reviewer to merge it for you.