Merge branch 'geo-registry-guide-docs' into 'master'

Geo: Fix Registry configuration guide

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/121168



Merged-by: Achilleas Pipinellis <axil@gitlab.com>
Approved-by: Achilleas Pipinellis <axil@gitlab.com>
Reviewed-by: Achilleas Pipinellis <axil@gitlab.com>
Reviewed-by: Valery Sizov <valery@gitlab.com>
Reviewed-by: Nick Westbury <nwestbury@gitlab.com>
Co-authored-by: Nick Westbury <nwestbury@gitlab.com>
Co-authored-by: Valery Sizov <valery@gitlab.com>

doc/administration/geo/replication/container_registry.md

@@ -73,12 +73,11 @@ To configure Container Registry replication:
 Make sure that you have Container Registry set up and working on
 the **primary** site before following the next steps.
 
-We need to make Container Registry send notification events to the
-**primary** site.
+To be able to replicate new container images, the Container Registry must send notification events to the
+**primary** site for every push. The token shared between the Container Registry and the web nodes on the
+**primary** is used to make communication more secure.
 
-For each application and Sidekiq node on the **primary** site:
-
-1. SSH into the node and login as the `root` user:
+1. SSH into your GitLab **primary** server and login as root (for GitLab HA, you only need a Registry node):
 
    ```shell
    sudo -i
@@ -107,15 +106,17 @@ For each application and Sidekiq node on the **primary** site:
    that starts with a letter. You can generate one with `< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c 32 | sed "s/^[0-9]*//"; echo`
 
    NOTE:
-   If you use an external Registry (not the one integrated with GitLab), you also have to specify
+   If you use an external Registry (not the one integrated with GitLab), you only need to specify
    the notification secret (`registry['notification_secret']`) in the
    `/etc/gitlab/gitlab.rb` file.
 
-   NOTE:
-   If you use GitLab HA, you also have to specify the notification secret (`registry['notification_secret']`) in
-   `/etc/gitlab/gitlab.rb` file for every web node.
+1. For GitLab HA only. Edit `/etc/gitlab/gitlab.rb` on every web node:
+
+   ```ruby
+   registry['notification_secret'] = '<replace_with_a_secret_token_generated_above>'
+   ```
 
-1. Reconfigure each node:
+1. Reconfigure each node you just updated:
 
    ```shell
    gitlab-ctl reconfigure