Adds a migrations file

docs/migrations.md

@@ -0,0 +1,27 @@
+# Managing database migrations
+
+Migrations are programmatic changes to your database. They are usually checked into Git.
+
+
+## Testing your migrations
+
+Inside your repository, create a new file inside the `.github/workflows` folder called `test-migrations.yml`.
+
+Copy this snippet inside the file, and the action will run whenever a new PR is created:
+
+```yaml
+name: 'test-migrations'
+on:
+  pull_request:
+
+jobs:
+  build: 
+    runs-on: ubuntu-latest
+    steps:
+        - uses: supabase/setup-cli@v1
+            with:
+            version: latest
+        - run: supabase init
+        - run: supabase db start
+```
+