docs: note about updating default branch

Author: jackyzha0

content/migrating from Quartz 3.md

@@ -32,6 +32,7 @@ When running `npx quartz create`, you will be prompted as to how to initialize y
 
 ## Things to update
 
+- You will need to update your deploy scripts. See the [[hosting]] guide for more details.
+- Ensure that your default branch on GitHub is updated from `hugo` to `v4`.
 - Some HTML layout may not be the same between Quartz 3 and Quartz 4. If you depended on a particular HTML hierarchy or class names, you may need to update your custom CSS to reflect these changes.
 - If you customized the layout of Quartz 3, you may need to translate these changes from Go templates back to JSX as Quartz 4 no longer uses Hugo. For components, check out the guide on [[creating components]] for more details on this.
-- You will also need to update your deploy scripts. See the [[hosting]] guide for more details.