bpo-43977: Update pattern matching language reference docs (GH-25917) (GH-26117)

* Update patma language reference with new changes to sequence and mapping

* update 3.10 whatsnew too
(cherry picked from commit 53c91ac5253bf1cb3cb20e1345e798a53f4c3517)

Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>

Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
2 files changed