Use the new gitlab-shell authorized-keys helper in documentation

GITLAB_SHELL_VERSION

-5.10.3
+5.11.0

doc/administration/operations/fast_ssh_key_lookup.md

@@ -25,34 +25,12 @@ GitLab Shell provides a way to authorize SSH users via a fast, indexed lookup
 to the GitLab database. GitLab Shell uses the fingerprint of the SSH key to
 check whether the user is authorized to access GitLab.
 
-Create the directory `/opt/gitlab-shell` first:
-
-```bash
-sudo mkdir -p /opt/gitlab-shell
-```
-
-Create this file at `/opt/gitlab-shell/authorized_keys`:
-
-```
-#!/bin/bash
-
-if [[ "$1" == "git" ]]; then
-  /opt/gitlab/embedded/service/gitlab-shell/bin/authorized_keys $2
-fi
-```
-
-Set appropriate ownership and permissions:
-
-```
-sudo chown root:git /opt/gitlab-shell/authorized_keys
-sudo chmod 0650 /opt/gitlab-shell/authorized_keys
-```
-
-Add the following to `/etc/ssh/sshd_config` or to `/assets/sshd_config` if you
-are using Omnibus Docker:
+Add the following to your `sshd_config` file. This is usuaully located at
+`/etc/ssh/sshd_config`, but it will be `/assets/sshd_config` if you're using
+Omnibus Docker:
 
 ```
-AuthorizedKeysCommand /opt/gitlab-shell/authorized_keys %u %k
+AuthorizedKeysCommand /opt/embedded/gitlab-shell/bin/gitlab-shell-authorized-keys-check git %u %k
 AuthorizedKeysCommandUser git
 ```
 
@@ -70,7 +48,7 @@ Confirm that SSH is working by removing your user's SSH key in the UI, adding a
 new one, and attempting to pull a repo.
 
 > **Warning:** Do not disable writes until SSH is confirmed to be working
-perfectly because the file will quickly become out-of-date.
+perfectly, because the file will quickly become out-of-date.
 
 In the case of lookup failures (which are not uncommon), the `authorized_keys`
 file will still be scanned. So git SSH performance will still be slow for many