docs(connector-facebook): readme (#1162)

packages/connector-facebook/README.md

@@ -1,2 +1,56 @@
-### FB Social Connector README
-placeholder
+# Facebook
+
+The Facebook connector provides a concise way for your application to use Facebook's OAuth 2.0 authentication system.
+
+## Register a Facebook developer account
+
+[Register as a Facebook Developer](https://developers.facebook.com/docs/development/register/) if you don't already have one
+
+## Set up a Facebook app
+
+1. Visit the [Apps](https://developers.facebook.com/apps) page.
+2. Click your existing app or [create a new one](https://developers.facebook.com/docs/development/create-an-app) if needed.
+   - The selected [app type](https://developers.facebook.com/docs/development/create-an-app/app-dashboard/app-types) is up to you, but it should have the product **Facebook Login**.
+3. On the app dashboard page, scroll to the **Add a product** section and click the **Set up** button on the **Facebook Login** card.
+4. Skip the Facebook Login Quickstart page, and click the sidebar -> **Products** -> **Facebook Login** -> **Settings**.
+5. In the Facebook Login Settings page, fill `${your_logto_origin}/callback/facebook-universal` in the **Valid OAuth Redirect URIs** field. E.g.:
+    - `https://logto.dev/callback/facebook-universal` for production
+    - `https://localhost:3001/callback/facebook-universal` for testing in the local environment
+6. Click the **Save changes** button at the bottom right corner.
+
+## Set up the Logto connector settings
+
+1. In the Facebook app dashboard page, click the sidebar -> **Settings** -> **Basic**.
+2. You will see the **App ID** and **App secret** on the panel.
+3. Click the **Show** button following the App secret input box to copy its content.
+4. Fill out the Logto connector settings:
+    - Fill out the `clientId` field with the string from **App ID**.
+    - Fill out the `clientSecret` field with the string from **App secret**.
+
+## Debug sign-in with the test users
+
+You can use the accounts of the test, developer, and admin users to test sign-in with the related app under both development and live [app modes](https://developers.facebook.com/docs/development/build-and-test/app-modes).
+
+You can also [take the app live](#take-the-facebook-app-live) directly so that any Facebook user can sign in with the app.
+
+- In the app dashboard page, click the sidebar -> **Roles** -> **Test Users**.
+- Click the **Create test users** button to create a testing user while testing.
+- Click the **Options** button of the existing test user, and you will see more operations, e.g., "Change name and password".
+
+## Take the Facebook app live
+
+Usually, only the test, admin, and developer users can sign in with the related app under [development mode](https://developers.facebook.com/docs/development/build-and-test/app-modes#development-mode).
+
+To enable normal Facebook users sign-in with the app in the production environment, you maybe need to switch your Facebook app to **[live mode](https://developers.facebook.com/docs/development/build-and-test/app-modes#live-mode)**, depending on the app type.
+E.g., the pure **business type** app doesn't have the **live** switch button, but it won't block your use.
+
+1. In the Facebook app dashboard page, click the sidebar -> **Settings** -> **Basic**.
+2. Fill out the **Privacy Policy URL** and **User data deletion** fields on the panel if required.
+3. Click the **Save changes** button at the bottom right corner.
+4. Click the **Live** switch button on the app top bar.
+
+## References
+
+- [Facebook Login - Documentation - Facebook for Developers](https://developers.facebook.com/docs/facebook-login/)
+    - [Manually Build a Login Flow](https://developers.facebook.com/docs/facebook-login/guides/advanced/manual-flow/)
+    - [Permissions Guide](https://developers.facebook.com/docs/facebook-login/guides/permissions)