#10046: small correction to atexit docs.

Doc/library/atexit.rst

@@ -12,8 +12,8 @@ functions.  Functions thus registered are automatically executed upon normal
 interpreter termination.
 
 Note: the functions registered via this module are not called when the program
-is killed by a signal, when a Python fatal internal error is detected, or when
-:func:`os._exit` is called.
+is killed by a signal not handled by Python, when a Python fatal internal error
+is detected, or when :func:`os._exit` is called.
 
 
 .. function:: register(func, *args, **kargs)