git: openjdk/jfx25u: master: 8304008: Update README.md and CONTRIBUTING.md for jfx update repos

[Kevin Rushforth]

Changeset: 8e835833
Branch: master
Author:    Kevin Rushforth <kcr at openjdk.org>
Date:      2025-07-22 12:38:54 +0000
URL:       https://git.openjdk.org/jfx25u/commit/8e83583379a474cb1812cdc32ad372e2f8afc51a

8304008: Update README.md and CONTRIBUTING.md for jfx update repos

Reviewed-by: jvos
Backport-of: 632792d4e7a6399c156df99b1cf69faba476a8c6

! CONTRIBUTING.md
! README.md