Strip future-focused language

Focus on the now, and the existence of a
discussion, rather than saying we have 
future plans for a feature.

doc/administration/operations/gitlab_sshd.md

@@ -27,9 +27,8 @@ If you are considering switching from OpenSSH to `gitlab-sshd`, consider these c
 
 - `gitlab-sshd` supports the PROXY protocol. It can run behind proxy servers that rely
   on it, such as HAProxy. The PROXY protocol is not enabled by default, but [it can be enabled](#proxy-protocol-support).
-- `gitlab-sshd` **does not** support SSH certificates. For more details, see the
-  [confidential issue](../../user/project/issues/confidential_issues.md)
-  `https://gitlab.com/gitlab-org/gitlab-shell/-/issues/495`.
+- `gitlab-sshd` does not support SSH certificates. For discussion about adding them,
+  see [issue 655](https://gitlab.com/gitlab-org/gitlab-shell/-/issues/655).
 
 ## Enable `gitlab-sshd`