Issue #27076: Doc, comment and tests spelling fixes
Most fixes to Doc/ and Lib/ directories by Ville Skyttä.
diff --git a/Lib/test/test_email/test__header_value_parser.py b/Lib/test/test_email/test__header_value_parser.py
index d028f74..f7ac0e3 100644
--- a/Lib/test/test_email/test__header_value_parser.py
+++ b/Lib/test/test_email/test__header_value_parser.py
@@ -2498,7 +2498,7 @@
# Note that it is undefined what we should do for error recovery when
# there are duplicate parameter names or duplicate parts in a split
# part. We choose to ignore all duplicate parameters after the first
- # and to take duplicate or missing rfc 2231 parts in apperance order.
+ # and to take duplicate or missing rfc 2231 parts in appearance order.
# This is backward compatible with get_param's behavior, but the
# decisions are arbitrary.