Update ops/testing.py

Co-authored-by: Ben Hoyt <[email protected]>

ops/testing.py

@@ -1602,7 +1602,7 @@ def handle_exec(self,
           (equivalent to ``ExecResult(exit_code=0, stdout=str_or_bytes)``) or an integer
           (equivalent to ``ExecResult(exit_code=return_value)``).
 
-        - A ``result``: For simulations don't need to inspect the execution argument, the
+        - A ``result``: For simulations that don't need to inspect the ``exec`` arguments, the
           registration can be further simplified using the ``result`` argument. This is equivalent
           to setting ``handler=lambda _: result``.