Adjust formatting on Schedule Revision History

gtfs/spec/en/revision-history.md

@@ -1,15 +1,15 @@
 ### Revision History
 
-### September 2024
+#### September 2024
 * Clarify presence and use of from/to_stop_id & from/to_trip_id fields in transfers.txt. See [discussion](https://github.com/google/transit/pull/455).
 * Added validity rules for polygons in GeoJSON files. See [discussion](https://github.com/google/transit/pull/476).
 
-### August 2024
+#### August 2024
 * Change stops.txt presence because of demand responsive services. See [discussion](https://github.com/google/transit/pull/472).
 * Clarify intended use for timepoint in stop_times.txt. See [discussion](https://github.com/google/transit/pull/474).
 * Add that headsigns are recommended. See [discussion](https://github.com/google/transit/pull/485).
 
-### July 2024
+#### July 2024
 * Update requirement for feed_info.txt. See [discussion](https://github.com/google/transit/pull/460).
 * Add that shapes should be included. See [discussion](https://github.com/google/transit/pull/470).