fix: add placeholder to .env.example

.env.example

@@ -1,9 +1,14 @@
+# API Endpoint
 VITE_API_URL=
 
-CMS_SECRET=
-CMS_POSTGRES_URL=
+# Payload CMS Secret Key (minimum 32 characters)
+CMS_SECRET=your-very-long-secret-key
 
-CMS_STORAGE_ENDPOINT=
-CMS_STORAGE_ACCESS_KEY_ID=
-CMS_STORAGE_SECRET_ACCESS_KEY=
+# PostgreSQL Connection String
+CMS_POSTGRES_URL=postgres://user:password@host:port/database
+
+# S3 Storage Configuration
+CMS_STORAGE_ENDPOINT=https://your-s3-endpoint.com
+CMS_STORAGE_ACCESS_KEY_ID=your-access-key-id
+CMS_STORAGE_SECRET_ACCESS_KEY=your-secret-access-key
 CMS_STORAGE_REGION=ap-southeast-1