update url for rhel6 so it doesn't error out

Author: jaimergp

src/user/announcements.rst

@@ -32,7 +32,7 @@ virtual package, but the details of how we will achieve this are still being wor
 As you may be aware, we have delayed the deprecation of our CentOS 6 build
 system the ``linux64`` platform several times. We have now set a formal deprecation
 date to be June 30, 2024. This date matches the
-`end of extended life-cycle support <https://endoflife.software/operating-systems/linux/red-hat-enterprise-linux-rhel>`_
+`end of extended life-cycle support <https://access.redhat.com/articles/4038291>`__
 from RedHat for RHEL 6. After this date, we build packages against
 CentOS 7 by default for ``linux64``.