Distinguish CNG & Omnibus defaults for fast SSH key lookup

doc/administration/operations/fast_ssh_key_lookup.md

@@ -31,7 +31,8 @@ able to accept a fingerprint. Check the version of OpenSSH on your server with `
 
 ## Fast lookup is required for Geo **(PREMIUM)**
 
-By default, GitLab manages an `authorized_keys` file that is located in the
+Unlike [Cloud Native GitLab](https://docs.gitlab.com/charts/), Omnibus GitLab by default
+manages an `authorized_keys` file that is located in the
 `git` user's home directory. For most installations, this will be located under
 `/var/opt/gitlab/.ssh/authorized_keys`, but you can use the following command to locate the `authorized_keys` on your system: