Add doc to grist sync

src/meal_manager/main.py

@@ -433,7 +433,14 @@ def get_event_attendance_pdf(event_id: int, session: SessionDep):
 
 @app.get("/event/{event_id}/sync_with_grist")
 def sync_with_grist_route(event_id: int, session: SessionDep, user: StrictUserDep):
+    """
+    Synchronizes the specified event with Grist and redirects the user.
 
+    This function retrieves the event by its identifier, synchronizes it with Grist,
+    and then redirects the user to the event page with a success message.
+
+    TODO: Error handling
+    """
     statement = select(Event).where(Event.id == event_id)
     event = session.scalars(statement).one()