doc: Add link for "Setup on a Cloud Server" to README

Author: Khader-1

README.md

@@ -100,6 +100,12 @@ Two specific points to expand on:
 4. Start the app with `flutter run`, or from your IDE.
 
 
+### More guides for setting up
+
+- [Setup on a Cloud Server][cloud-server]
+
+[cloud-server]: https://github.com/zulip/zulip-flutter/blob/main/docs/setup.md#on-a-cloud-server
+
 ### Flutter version
 
 While in the beta phase, we use the latest Flutter from Flutter's