bpo-45277: Fix typo in codecs doc (GH-28555)

encoding => encode
(cherry picked from commit 4c0fc65)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Doc/library/codecs.rst

@@ -923,7 +923,7 @@ it's a device to determine the storage layout of the encoded bytes, and vanishes
 once the byte sequence has been decoded into a string; as a ``ZERO WIDTH
 NO-BREAK SPACE`` it's a normal character that will be decoded like any other.
 
-There's another encoding that is able to encoding the full range of Unicode
+There's another encoding that is able to encode the full range of Unicode
 characters: UTF-8. UTF-8 is an 8-bit encoding, which means there are no issues
 with byte order in UTF-8. Each byte in a UTF-8 byte sequence consists of two
 parts: marker bits (the most significant bits) and payload bits. The marker bits