Adds a script for managing types

docs/generating-types.md

@@ -0,0 +1,33 @@
+# Generating Types
+
+You can use the Supabase CLI to automatically generate Typescript definitions from your Postgres database. You can then pass these definitions to your `supabase-js` client and get end-to-end type safety across client, server, and database.
+
+## Testing your migrations
+
+Inside your repository, create a new file inside the `.github/workflows` folder called `generate-types.yml`.
+
+Copy this snippet inside the file, and the action will run whenever a new PR is created:
+
+```yaml
+name: 'generate-types'
+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
+        - name: Verify generated types match Postgres schema
+          run: |
+            supabase gen types typescript --local > schema.gen.ts
+            if ! git diff --ignore-space-at-eol --exit-code --quiet schema.gen.ts; then
+              echo "Detected uncommitted changes after build. See status below:"
+              git diff
+              exit 1
+            fi
+```