More docstring fixes

Fix a couple of errors in docstrings

synapse/state.py

@@ -434,8 +434,8 @@ def resolve_events_with_state_map(state_sets, state_map):
             state_sets.
 
     Returns
-        dict[(str, str), synapse.events.FrozenEvent]:
-            a map from (type, state_key) to event.
+        dict[(str, str), str]:
+            a map from (type, state_key) to event_id.
     """
     if len(state_sets) == 1:
         return state_sets[0]
@@ -497,8 +497,8 @@ def resolve_events_with_factory(state_sets, state_map_factory):
             a Deferred of dict of event_id to event.
 
     Returns
-        Deferred[dict[(str, str), synapse.events.FrozenEvent]]:
-            a map from (type, state_key) to event.
+        Deferred[dict[(str, str), str]]:
+            a map from (type, state_key) to event_id.
     """
     if len(state_sets) == 1:
         defer.returnValue(state_sets[0])