Modify migration workflow to include another git add

polaris.shopify.com/content/version-guides/migrating-from-v11-to-v12.md

@@ -47,8 +47,10 @@ git stash push $(grep -r -l "polaris-migrator:" $(git ls-files -m))
 git add .
 # Format staged files only
 git diff --staged --name-only | xargs npx prettier --write
+# Stage formatted files
+git add .
 #  Commit automatic migration
-git commit -m "Migrate X custom properties from Polaris v11 to v12"
+git commit -m "Migrate X from Polaris v11 to v12"
 ```
 
 The polaris migrator could insert comments or skip instances that are unsafe to automatically migrate. You will need to resolve those issues in the next manual migration step.