add comment to resource tracker __del__

Author: luccabb

Lib/multiprocessing/resource_tracker.py

@@ -213,6 +213,9 @@ def _send(self, cmd, name, rtype):
             nbytes, len(msg))
 
     def __del__(self):
+        # making sure child processess are cleaned before ResourceTracker
+        # gets destructed.
+        # see https://github.com/python/cpython/issues/88887
         try:
             self._stop()
         except: