🦎 docs: note scmap proto regeneration

Author: arduano

roborock/map/proto/b01_scmap.proto

@@ -1,3 +1,10 @@
+// Source of truth for the B01/Q7 SCMap schema.
+//
+// Regenerate the checked-in Python module after edits with:
+//   python -m grpc_tools.protoc -I. --python_out=. roborock/map/proto/b01_scmap.proto
+//
+// The generated file `b01_scmap_pb2.py` is checked in for runtime use and should
+// not be edited by hand.
 syntax = "proto2";
 
 package b01.scmap;