SCRIPTS: drop the HTML generation from announce-release

SCRIPTS: drop the HTML generation from announce-release

It has not been used over the last 5 years or so and systematically
requires manual removal. Let's just stop producing it. Also take
this opportunity to add the missing link to /discussions.

(cherry picked from commit 27baa3f9ff7f50f3751aa541daaa22a4ca577b5a)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit eae27fc288eb2d33fea53d60cbc5362d3eaffc01)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit b66643125323412a64bcfe978edb617cca4c15ce)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>