docs(connector-github): add GitHub README.md (en-US) (#1258)

packages/connector-alipay-native/README.md

@@ -27,7 +27,7 @@ Alipay Native connector works closely with Logto SDK on mobile platforms. It tak
     - Fill out the `privateKey` field with contents from the private key file mentioned in step 2. Remember to use '\n' to replace all newlines.
     - Fill out the `signType` filed with 'RSA2' due to the `Public key` signing mode we chose in step 7 of **Create And Configure Alipay Apps**.
 
-## Settings
+### Config types
 
 |    Name    |     Type    |   Enum values   |
 |:----------:|:-----------:|:---------------:|

packages/connector-alipay/README.md

@@ -27,7 +27,7 @@ Alipay Web connector is designed for desktop Web applications. It takes advantag
     - Fill out the `privateKey` field with contents from the private key file mentioned in step 2. Remember to use '\n' to replace all newlines.
     - Fill out the `signType` filed with 'RSA2' due to the `Public key` signing mode we chose in step 7 of **Create And Configure Alipay Apps**.
 
-## Settings
+### Config types
 
 |    Name    |     Type    |   Enum values   |
 |:----------:|:-----------:|:---------------:|

packages/connector-facebook/README.md

@@ -27,7 +27,7 @@ The Facebook connector provides a concise way for your application to use Facebo
     - Fill out the `clientId` field with the string from **App ID**.
     - Fill out the `clientSecret` field with the string from **App secret**.
 
-## Settings
+### Config types
 
 |     Name     |  Type  |
 |:------------:|:------:|

packages/connector-github/README.md

@@ -1,2 +1,45 @@
-### Github Social Connector README
-placeholder
+# Github
+
+The GitHub connector enables users to have access to your application using their own GitHub accounts via GitHub OAuth 2.0 authentication protocol.
+
+## Sign in with GitHub account
+
+Go to the [GitHub website](https://github.com/) and sign in with your GitHub account. You may register a new account if you don't have one.
+
+## Create and configure GitHub OAuth app
+
+Follow the [Creating an OAuth App](https://docs.github.com/en/developers/apps/building-oauth-apps/creating-an-oauth-app) guide, and register a new application.
+
+Name your new OAuth application in **Application name** and fill up **Homepage URL** of the app.
+You can leave **Application description** field blank and customize **Authorization callback URL** as `${your_logto_origin}/callback/github-universal`.
+
+We suggest not to check the box before **Enable Device Flow**, or users who sign in with GitHub on mobile devices must confirm the initial sign-in action in the GitHub app. Many GitHub users do not install the GitHub mobile app on their phones, which could block the sign-in flow. Please ignore our suggestion if you are expecting end-users to confirm their sign-in flow.
+
+You can also enable end-users to sign in with GitHub accounts by [creating a GitHub app](https://docs.github.com/en/developers/apps/building-github-apps/creating-a-github-app).
+
+## Managing GitHub OAuth apps
+
+Go to the [OAuth Apps page](https://github.com/settings/developers) and you can add, edit or delete existing OAuth apps.
+You can also find `Client ID` and generate `Client secrets` in OAuth app detail pages.
+
+As for managing GitHub Apps we mentioned in the last section, go to the [GitHub Apps page](https://github.com/settings/apps).
+
+## Compose the connector JSON
+
+Fill out the `clientId` and `clientSecret` field with **Client ID** and **Client Secret** you've got from OAuth app detail pages mentioned in the previous section.
+
+Here is an example of GitHub connector config JSON.
+
+```json
+{
+    "clientID": "<your-client-id>",
+    "clientSecret": "<your-client-secret>"
+}
+```
+
+### Config types
+
+| Name         | Type   |
+|--------------|--------|
+| clientId     | string |
+| clientSecret | string |

packages/connector-google/README.md

@@ -47,7 +47,7 @@ Now you should have the Google OAuth 2.0 consent screen configured.
 - 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
+### Config types
 
 |     Name     |  Type  |
 |:------------:|:------:|