Merge branch 'if-721-fix_release_version' into 'master'

Fix release version for smartcard auth in doc

See merge request gitlab-org/gitlab-ee!8734

doc/administration/auth/smartcard.md

 # Smartcard authentication
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/726) in
-[GitLab Premium](https://about.gitlab.com/pricing/) 11.5 as an experimental
+[GitLab Premium](https://about.gitlab.com/pricing/) 11.6 as an experimental
 feature. Smartcard authentication may change or be removed completely in future
 releases.