bpo-40745: Fix typos in NewType docs (GH-20379)

(cherry picked from commit 2b0e654)

Co-authored-by: ziheng <[email protected]>

Author: miss-islington

Doc/library/typing.rst

@@ -1021,9 +1021,9 @@ The module defines the following classes, functions and decorators:
    ``List[ForwardRef("SomeClass")]``.  This class should not be instantiated by
    a user, but may be used by introspection tools.
 
-.. function:: NewType(typ)
+.. function:: NewType(name, tp)
 
-   A helper function to indicate a distinct types to a typechecker,
+   A helper function to indicate a distinct type to a typechecker,
    see :ref:`distinct`. At runtime it returns a function that returns
    its argument. Usage::