gh-84910: Tweak IDLE Glossary entry (GH-95866)

Link "IDLE" to its doc and add 'and Learning' to its expansion,
as in the doc.
(cherry picked from commit 3646f6cd880f8f91e189a2fe44a687798aa1fef1)

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