[3.11] GH-97950: Use new-style index directive ('keyword') (GH-104153) (#104155)

GH-97950: Use new-style index directive ('keyword') (GH-104153)

* Uncomment keyword removal in pairindextypes

* Use new-style index directive ('keyword') - Reference
(cherry picked from commit 33ca322c50baa5152afe388fb3b8b7d63dc5a9b9)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>