docs: google universal connector (#1040)

packages/connector-google/README.md

@@ -1,2 +1,58 @@
-### Google Social Connector README
-placeholder
+# Google
+
+The Google connector provides a succinct way for your application to use Google’s OAuth 2.0 authentication system.
+
+## Set up a project in the Google API Console
+
+- Visit the [Google API Console](https://console.developers.google.com) and sign in with your Google account.
+- Click the **Select a project** button on the top menu bar, and click the **New Project** button to create a project.
+- In your newly created project, click the **APIs & Services** to enter the **APIs & Services** menu.
+
+## Configure your consent screen
+
+### Configure and register your application
+
+- On the left **APIs & Services** menu, click the **OAuth consent screen** button.
+- Choose the **User Type** you want, and click the **Create** button. (Note: If you select **External** as your **User Type**, you will need to add test users later.)
+
+Now you will be on the **Edit app registration** page.
+
+### Edit app registration
+
+#### Config OAuth consent screen
+
+- Follow the instructions to fill out the **OAuth consent screen** form.
+- Click **SAVE AND CONTINUE** to continue.
+
+#### Config Scopes
+
+- Click **ADD OR REMOVE SCOPES** and select `../auth/userinfo.email`, `../auth/userinfo.profile` and `openid` in the popup drawer, and click **UPDATE** to finish.
+- Fill out the form as you need.
+- Click **SAVE AND CONTINUE** to continue.
+
+#### Add Test Users (External user type only)
+
+- Click **ADD USERS** and add test users to allow these users to access your application while testing.
+- Click **SAVE AND CONTINUE** to continue.
+
+Now you should have the Google OAuth 2.0 consent screen configured.
+
+## Obtain OAuth 2.0 credentials
+
+- On the left **APIs & Services** menu, click the **Credentials** button.
+- On the **Credentials** page, click the **+ CREATE CREDENTIALS** button on the top menu bar, and select **OAuth client ID**.
+- On the **Create OAuth client ID** page, select **Web application** as the application type.
+- Fill out the basic information for your application.
+- Click **+ Add URI** to add an authorized domain to the **Authorized JavaScript origins** section. This is the domain that your logto authorization page will be served from. In our case, this will be `${your_logto_origin}`. e.g.`https://logto.dev`.
+- Click **+ Add URI** in the ****Authorized redirect URIs**** section to set up the ****Authorized redirect URIs****, which redirect the user to the application after logging in. In our case, this will be `${your_logto_origin}/callback/google-universal`. e.g. `https://logto.dev/callback/google-universal`.
+- Click **Create** to finish and then you will get the **Client ID** and **Client Secret**.
+
+## Settings
+
+| Name | Type |
+| --- | --- |
+| clientId | string |
+| clientSecret | string |
+
+## References
+* [Google Identity: Setting up OAuth 2.0](https://developers.google.com/identity/protocols/oauth2/openid-connect#appsetup)