minor rewording

Author: mikeshardmind

docs/spec/narrowing.rst

@@ -274,12 +274,13 @@ Because it is possible to attempt to narrow B,
 but A does not have appropriate information about B
 (or any other unknown subclass of A!) it's not possible to safely narrow
 in either direction. The general rule for generics is that if you do not know
-all the places a generic class is generic and do not enough of them to be
+all the places a generic class is generic and do not check enough of them to be
 absolutely certain, you cannot return True, and if you do not have a definitive
 counter example to the type to be narrowed to you cannot return False.
 In practice, if soundness is prioritized over an unsafe narrowing,
-not knowing what you don't know is solvable by erroring out
-or by making the class to be narrowed final to avoid such a situation.
+not knowing what you don't know is solvable by either
+erroring out when neither return option is safe, or by making the class to be
+narrowed final to avoid such a situation.
 
 In practice, such correctness is not always neccessary, and may work against
 your needs. for example, if you trust that users implementing