add echo

dev/gen-protos.sh

@@ -118,6 +118,7 @@ done
 
 black --config $SPARK_HOME/dev/pyproject.toml gen/proto/python
 
+# Last step copy the result files to the destination module.
 for f in `find gen/proto/python -name "*.py*"`; do
   cp $f $OUTPUT_PATH
 done