Add feature branch update instructions

README.md

@@ -13,6 +13,40 @@ This project has adopted the [Microsoft Open Source Code of Conduct](https://ope
 For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or
 contact [[email protected]](mailto:[email protected]) with any additional questions or comments.
 
+## For maintainers: Updating feature branches
+
+This repository uses feature branches to associate code with specific modules on Microsoft Learn. Any changes you make to the default branch will likely need to be propagated to each feature branch in this repo. A common example is when we need to update Node packages in `package.json`.
+
+Here's one way to update the remote feature branches when you make a change to the default branch. Note that this process deletes all local branches except for `main`.
+
+```bash
+# Synchronize with the remote main branch
+git checkout main
+git pull origin main
+# Delete all local branches except for main
+git branch | grep -ve "main" | xargs git branch -D
+# List all remote branches except for main
+branches=$(git branch -r 2> /dev/null | grep -ve "main" | cut -d "/" -f 2)
+# Synchronize each branch with main and push the result
+while IFS= read -r branch; do
+    # Fetch and switch to feature branch
+    git fetch origin $branch
+    git checkout $branch
+    # Ensure local environment is free of extra files
+    git clean -xdf
+    # Merge down main
+    git merge --no-ff main
+    # Break out if merge failed
+    if [ $? -ne 0 ]; then
+        break
+    fi
+    # Push update
+    git push origin $branch
+done <<< "$branches"
+# Switch back to main
+git checkout main
+```
+
 # Legal Notices
 
 Microsoft and any contributors grant you a license to the Microsoft documentation and other content