Add EE version and CE issue link

doc/administration/operations/fast_ssh_key_lookup.md

 # Fast lookup of authorized SSH keys in the database
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/1631) in 
-> [GitLab Enterprise Edition](https://about.gitlab.com/gitlab-ee) 9.3.
+> [GitLab Enterprise Edition Standard](https://about.gitlab.com/gitlab-ee) 9.3.
 >
-> Available in GitLab Community Edition 10.4.
+> [Available in](https://gitlab.com/gitlab-org/gitlab-ee/issues/3953) GitLab
+> Community Edition 10.4.
 Regular SSH operations become slow as the number of users grows because OpenSSH
 searches for a key to authorize a user via a linear search. In the worst case,