fix typos

googlemock/docs/cheat_sheet.md

@@ -857,12 +857,12 @@ you can do it earlier:
 using ::testing::Mock;
 ...
 // Verifies and removes the expectations on mock_obj;
-// returns true iff successful.
+// returns true if successful.
 Mock::VerifyAndClearExpectations(&mock_obj);
 ...
 // Verifies and removes the expectations on mock_obj;
 // also removes the default actions set by ON_CALL();
-// returns true iff successful.
+// returns true if successful.
 Mock::VerifyAndClear(&mock_obj);
 ```