Add docstring for init request manager

src/primaite/simulator/domain/controller.py

@@ -80,6 +80,11 @@ class DomainController(SimComponent):
         super().__init__(**kwargs)
 
     def _init_request_manager(self) -> RequestManager:
+        """
+        Initialise the request manager.
+
+        More information in user guide and docstring for SimComponent._init_request_manager.
+        """
         rm = super()._init_request_manager()
         # Action 'account' matches requests like:
         # ['account', '<account-uuid>', *account_action]