Issue #27076: Doc, comment and test function name spelling fixes

Most fixes to Doc/ and Lib/ directories by Ville Skyttä.
diff --git a/Lib/test/test_cookielib.py b/Lib/test/test_cookielib.py
index d272d12..a6568d7 100644
--- a/Lib/test/test_cookielib.py
+++ b/Lib/test/test_cookielib.py
@@ -1760,7 +1760,7 @@
             key = "%s_after" % cookie.value
             counter[key] = counter[key] + 1
 
-            # a permanent cookie got lost accidently
+            # a permanent cookie got lost accidentally
         self.assertEqual(counter["perm_after"], counter["perm_before"])
             # a session cookie hasn't been cleared
         self.assertEqual(counter["session_after"], 0)