feat(docs): Mention the update script in migration docs (#13385)

* ✏️ docs for migration script

* Update develop-docs/backend/application-domains/database-migrations/index.mdx

Co-authored-by: Michael Sun <[email protected]>

---------

Co-authored-by: Michael Sun <[email protected]>

Author: leeandher

develop-docs/backend/application-domains/database-migrations/index.mdx

@@ -54,7 +54,19 @@ Note that if you have added a new model, you also need to import the model in `_
 
 When merging to master you might notice a conflict with `migrations_lockfile.txt`. This file is in place to help us avoid merging two migrations with the same migration number to master, and if you're conflicting with it then it's likely someone has committed a migration ahead of you.
 
-To resolve this, rebase against latest master, delete your current migration and then regenerate it. If your migration was custom, just save the operations in a text file somewhere so that you can reapply them on the regenerated migration.
+### Automatically Resolving Conflicts
+
+There is a [useful script](https://github.com/getsentry/sentry/blob/master/bin/update-migration) for automatically moving your migration to the top of the migration history.
+
+```bash
+bin/update-migration <migration_name>
+```
+
+It will rename the migration, modify it to depend on the latest migration, and update the lockfile and the name of any tests if they exist.
+
+### Manually Resolving Conflicts
+
+To perform the steps manually, rebase against latest master, delete your current migration and then regenerate it. If your migration was custom, just save the operations in a text file somewhere so that you can reapply them on the regenerated migration.
 
 Always commit the changes to `migrations_lockfile.txt` with your migration.