feat: Add base path support for Formbricks (#6853)

.env.example

@@ -9,8 +9,12 @@
 WEBAPP_URL=http://localhost:3000
 
 # Required for next-auth. Should be the same as WEBAPP_URL
+# If your pplication uses a custom base path, specify the route to the API endpoint in full, e.g. NEXTAUTH_URL=https://example.com/custom-route/api/auth
 NEXTAUTH_URL=http://localhost:3000
 
+# Can be used to deploy the application under a sub-path of a domain. This can only be set at build time
+# BASE_PATH=
+
 # Encryption keys
 # Please set both for now, we will change this in the future