Add an upgrade notice on the release page

Summary:
This makes it clearer to businesses that 0.22.x versions are needed to stay compatible
after Nov 15th.

Test Plan:

make serve

Navigate to:
http://localhost:4000/releases/

Ensure no regressions:
http://localhost:4000/releases/#0.22.4
http://localhost:4000/releases/#0.22.3

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D8089