Spelling fixes to docs, docstrings, and comments (GH-6374)

diff --git a/Lib/typing.py b/Lib/typing.py
index d45502f..8329607 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -732,7 +732,7 @@
         return (self.__origin__,)
 
     def __getattr__(self, attr):
-        # We are carefull for copy and pickle.
+        # We are careful for copy and pickle.
         # Also for simplicity we just don't relay all dunder names
         if '__origin__' in self.__dict__ and not _is_dunder(attr):
             return getattr(self.__origin__, attr)