DOCS: New page on how to upgrade coldfront

docs/pages/upgrading.md

@@ -125,3 +125,76 @@ PLUGIN_SLURM=True
 SLURM_IGNORE_USERS=root,admin,testuser
 SLURM_SACCTMGR_PATH=/usr/bin/sacctmgr
 ```
+
+## Upgrading with Git
+
+This guide demonstrates one way to use `git` to upgrade your ColdFront codebase to the latest release or the `main` branch. 
+
+### Git setup
+
+You will need to set up two git remotes:
+
+- `origin` -> Your organization's Git repo for ColdFront
+- `upstream` -> `$ git remote add upstream https://github.com/ubccr/coldfront.git`
+
+Next, you will want to have at least three git branches to work with:
+
+- `<custom>` -> This is your default branch, containing your organization's ColdFront codebase
+- `main` -> This branch tracks the `main` branch of the ColdFront project
+- `staged_upgrade` -> This is based on your `custom` branch, used for resolving merge conflicts
+
+```sh
+# let's assume you only have a `main` branch and a `custom` branch
+$ git checkout main
+
+# pull in the latest changes
+$ git pull upstream main
+# or checkout a new tagged release
+$ git tag -l
+$ git checkout v1.x.x
+
+$ git checkout custom
+
+# make a new branch off of your `custom` branch
+$ git checkout -b staged_upgrade
+$ git merge main
+
+# resolve any conflicts in your text editor
+$ git commit -m "merge bring in latest changes"
+```
+
+The trickiest part of the process will be to resolve any conflicts from merging `main` into your `staged_upgrade` branch. This is where you want to make sure your local customizations are kept in tact from the upgrade. 
+
+### Database Migrations
+
+After your code is merged, migrate your database to accomodate changes to models:
+
+```sh
+# make sure you have activated your virtual environment
+$ source .venv/bin/activate
+$ coldfront makemigrations --merge
+$ coldfront migrate
+```
+
+### Testing
+
+Restart your server in your testing environment to confirm everything is working as expected. 
+
+```
+# either in a local dev environment
+$ DEBUG=True uv run coldfront runserver
+# or on a test server environment
+$ sudo systemctl restart gunicorn
+```
+
+If everything looks good, merge your `staged_upgrade` branch into your default branch:
+
+```sh
+$ git checkout custom
+$ git merge staged_upgrade
+# update your remote
+$ git push origin custom
+$ git branch -d staged_upgrade
+```
+
+Your organization's ColdFront codebase should now have the latest updates from the upstream ColdFront project. If you want to enable some of the newest ColdFront features, you may need to [install](/install#installation-methods) newer packages.