Feat(docs): add OIDC samples to env example

.env.example

@@ -12,6 +12,19 @@ DATABASE_URL=postgresql://readur:readur_password@localhost:5432/readur
 JWT_SECRET=your-super-secret-jwt-key-change-this-in-production
 SERVER_ADDRESS=0.0.0.0:8000
 
+# Authentication Configuration
+# Enable/disable local username/password authentication (default: true)
+# When disabled, only OIDC authentication is available
+ALLOW_LOCAL_AUTH=true
+
+# OIDC Configuration (optional - see docs/oidc-setup.md for details)
+# OIDC_ENABLED=true
+# OIDC_CLIENT_ID=your-client-id
+# OIDC_CLIENT_SECRET=your-client-secret
+# OIDC_ISSUER_URL=https://accounts.google.com
+# OIDC_REDIRECT_URI=https://your-domain.com/api/auth/oidc/callback
+# OIDC_AUTO_REGISTER=true
+
 # File Storage & Upload
 UPLOAD_PATH=./uploads
 ALLOWED_FILE_TYPES=pdf,png,jpg,jpeg,tiff,bmp,gif,txt,rtf,doc,docx