Added documentation to the sync decorator method

ably/decorator/sync.py

@@ -35,9 +35,17 @@ def wrapper(*args, **kwargs):
         except:
             pass
         ably_eventloop = get_custom_event_loop()
+
+        # Handle calls from ably_eventloop on the same loop, return awaitable
+        if caller_eventloop is not None and caller_eventloop == ably_eventloop:
+            return ably_eventloop.create_task(fn(*args, **kwargs))
+
+        # Post external calls on ably_eventloop, return awaitable on calling eventloop
         future = asyncio.run_coroutine_threadsafe(fn(*args, **kwargs), ably_eventloop)
         if caller_eventloop is not None and caller_eventloop.is_running():
             return asyncio.wrap_future(future)
+
+        # If called from regular function instead of coroutine, block till result is available
         return future.result()
 
     return wrapper