SCRIPTS: announce-release: update the doc's URL

Now that the doc is accessible on docs.haproxy.org via github pages,
let's update the URL.

(cherry picked from commit f0089d86ce43862453cc70e14057ec7935b7d0e5)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 8d314f9bb1461222a2004cb7ff0fab73f604925e)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
1 file changed