added self-hosting documentation for google

docs/mint.json

@@ -116,6 +116,12 @@
     {
       "group": "Self-host Infisical",
       "pages": [
+        {
+          "group": "Authentication",
+          "pages": [
+            "self-hosting/authentication/google"
+          ]
+        },
         {
           "group": "Deployment options",
           "pages": [

docs/self-hosting/authentication/google.mdx

@@ -0,0 +1,16 @@
+---
+title: "Google"
+description: "Learn to configure Google signin/signup when self-hosting Infisical."
+---
+To enable Google Auth for your Infisical project, you first need to set up a Google OAuth application.
+Follow Google's Setting up OAuth 2.0 documentation [here](https://support.google.com/googleapi/answer/6158849). After the setup, copy the Client ID and Client secret. You will need them below.
+
+## Configure Redirect URI
+Add the following URI to the Authorized redirect URIs section in the OAuth Client credentials page - `BASE_URL/api/v1/oauth/callback/google`. Replace BASE_URL with the URL of your hosted Infisical instance. 
+![google redirect](../../images/authentication-google-redirect.png)
+
+## General Configuration
+You wil need to configure the following [environment variables](https://infisical.com/docs/self-hosting/configuration/envars):
+
+- `CLIENT_ID_GOOGLE`: OAuth 2.0 Client ID obtained from the credentials page
+- `CLIENT_SECRET_GOOGLE`: OAuth 2.0 Client Secret obtained from the credentials page