revert example config to current default, but provide a more detailed comment

config/config.example.js

@@ -45,8 +45,16 @@ module.exports = {
  *  In such a case this should be also handled by NGINX, as documented in
  *  cryptpad/docs/example.nginx.conf (see the $main_domain variable)
  *
+ *  Note: you may provide multiple origins for the purpose of accessing
+ *  a development instance via different URLs, like so:
+ *  httpUnsafeOrigin: 'http://127.0.0.1:3000/ http://localhost:3000/',
+ *
+ *  Such configuration is not recommended for production instances,
+ *  as the development team does not actively test such configuration
+ *  and it may have unintended consequences in practice.
+ *
  */
-    httpUnsafeOrigin: 'http://127.0.0.1:3000/ http://localhost:3000',
+    httpUnsafeOrigin: 'http://localhost:3000/',
 
 /*  httpSafeOrigin is the URL that is used for the 'sandbox' described above.
  *  If you're testing or developing with CryptPad on your local machine then