Miscellaneous improvements to the typing docs (#105529)

Mostly, these are changes so that we use shorter sentences and shorter paragraphs. In particular, I've tried to make the first sentence introducing each object in the typing API short and declarative.

Lib/typing.py

@@ -561,7 +561,7 @@ def Never(self, parameters):
                 case str():
                     print("It's a str")
                 case _:
-                    never_call_me(arg)  # ok, arg is of type Never
+                    never_call_me(arg)  # OK, arg is of type Never
     """
     raise TypeError(f"{self} is not subscriptable")
 
@@ -594,13 +594,13 @@ def LiteralString(self, parameters):
 
         from typing import LiteralString
 
-        def run_query(sql: LiteralString) -> ...
+        def run_query(sql: LiteralString) -> None:
             ...
 
         def caller(arbitrary_string: str, literal_string: LiteralString) -> None:
-            run_query("SELECT * FROM students")  # ok
-            run_query(literal_string)  # ok
-            run_query("SELECT * FROM " + literal_string)  # ok
+            run_query("SELECT * FROM students")  # OK
+            run_query(literal_string)  # OK
+            run_query("SELECT * FROM " + literal_string)  # OK
             run_query(arbitrary_string)  # type checker error
             run_query(  # type checker error
                 f"SELECT * FROM students WHERE name = {arbitrary_string}"
@@ -2118,7 +2118,7 @@ def assert_type(val, typ, /):
     emits an error if the value is not of the specified type::
 
         def greet(name: str) -> None:
-            assert_type(name, str)  # ok
+            assert_type(name, str)  # OK
             assert_type(name, int)  # type checker error
     """
     return val