Update CONTRIBUTING.md

Co-authored-by: jrschat <54955683+jrschat@users.noreply.github.com>
signed-off-by: James Lagermann <james.lagermann@corelight.com>

CONTRIBUTING.md

@@ -36,3 +36,60 @@ When requesting or submitting new features, first consider whether it might be u
 - Commit Unix line endings.
 - Please use the Pi-hole brand: **Pi-hole** (Take a special look at the capitalized 'P' and a low 'h' with a hyphen)
 - (Optional fun) keep to the theme of Star Trek/black holes/gravity.
+
+## Forking and Cloning from GitHub to GitHub
+
+1. Fork <https://github.com/pi-hole/pi-hole/> to a repo under a namespace you control, or have permission to use, example: `https://github.com/<your_namespace>/<your_repo_name>/`.  You can do this from the github.com website.
+2. Clone `https://github.com/<your_namespace>/<your_repo_name>/` with the tool of you choice.
+3. To keep your fork in sync with our repo, add an upstream remote for pi-hole/pi-hole to your repo.
+    ```console
+    git remote add upstream https://github.com/pi-hole/pi-hole.git
+    ```
+4. Checkout the `development` branch from your clone `https://github.com/<your_namespace>/<your_repo_name>/`.
+5. Create a topic/branch, based on the `development` branch code. *Bonus fun to keep to the theme of Star Trek/black holes/gravity.*
+6. Make your changes and commit to your topic branch in your repo.
+7. Rebase your commits and squash any insignificant commits.  See notes below for an example.
+8. Merge `development` your branch and fix any conflicts.
+9. Open a Pull Request to merge your topic branch into our repo's `development` branch.
+- Keep in mind the technical requirements from above.
+
+## Forking and Cloning from GitHub to other code hosting sites
+
+- Forking is a GitHub concept and cannot be done from GitHub to other git based code hosting sites.  However, from those sites may be able to mirror a GitHub repo.
+1. To contribute from another code hosting site, you must first complete the steps above to fork our repo to a GitHub namespace you have permission to use, example: `https://github.com/<your_namespace>/<your_repo_name>/`.
+2. Create a repo in your code hosting site, for example: `https://gitlab.com/<your_namespace>/<your_repo_name>/`
+3. Follow the instructions from your code hosting site to create a mirror between `https://github.com/<your_namespace>/<your_repo_name>/` and `https://gitlab.com/<your_namespace>/<your_repo_name>/`.
+4. When you are ready to create a Pull Request (PR), follow the steps `(starting at step #6)` from [Forking and Cloning from GitHub to GitHub](#forking-and-cloning-from-github-to-github) and create the PR from `https://github.com/<your_namespace>/<your_repo_name>/`.
+
+## Notes for squashing commits with rebase
+
+- To rebase your commits and squash previous commits, you can use:
+    ```bash
+    git rebase -i your_topic_branch~(# of commits to combine)
+    ```
+- For more details visit [gitready.com](http://gitready.com/advanced/2009/02/10/squashing-commits-with-rebase.html)
+1. The following would combine the last four commits in the branch `mytopic`.
+    ```bash
+    git rebase -i mytopic~4
+    ```
+2. An editor window opens with the most recent commits indicated: (edit the commands to the left of the commit ID)
+    ```gitattributes
+    pick 9dff55b2 existing commit comments
+    squash ebb1a730 existing commit comments
+    squash 07cc5b50 existing commit comments
+    reword 9dff55b2 existing commit comments
+    ```
+3. Save and close the editor. The next editor window opens: (edit the new commit message).  *If you select reword for a commit, an additional editor window will open for you to edit the comment.*
+    ```console
+    new commit comments
+    Signed-off-by: yourname <your email address>
+    ```
+4. Save and close the editor for the rebase process to execute.  The terminal output should say something like the following:
+    ```console
+    Successfully rebased and updated refs/heads/mytopic.
+    ```
+5. Once you have a successful rebase, and before you sync your local clone, you have to force push origin to update your repo:
+    ```console
+    git push -f origin
+    ```
+6. Continue on from step #7 from [Forking and Cloning from GitHub to GitHub](#forking-and-cloning-from-github-to-github)