doc/cephadm: don't hardcode default oauth2-proxy image into docs

This makes it another place we need to update when changing
the default image which is easy to forget. Instead, we can
document how users can find the the image which will still
hold even if we change what the default image is.

Signed-off-by: Adam King <[email protected]>

Author: adk3798

doc/cephadm/services/oauth2-proxy.rst

@@ -119,17 +119,17 @@ A non-exhaustive list of important limitations for the `oauth2-proxy` service fo
 * Proper configuration of the IDP and OAuth2 parameters is crucial to avoid authentication failures. Misconfigurations can lead to access issues.
 
 
-Default images
-~~~~~~~~~~~~~~
+Container images
+~~~~~~~~~~~~~~~~
 
-The `oauth2-proxy` service typically uses the default container image:
+The container image the `oauth2-proxy` service will use can be found by running:
 
 ::
 
-    DEFAULT_OAUTH2_PROXY = 'quay.io/oauth2-proxy/oauth2-proxy:v7.2.0'
+    ceph config get mgr mgr/cephadm/container_image_oauth2_proxy
 
-Admins can specify the image to be used by changing the `container_image_oauth2_proxy` cephadm module option. If there were already running daemon(s),
-you must redeploy the daemon(s) to apply the new image.
+Admins can specify a custom image to be used by changing the `container_image_oauth2_proxy` cephadm module option.
+If there were already running daemon(s), you must also redeploy the daemon(s) for them to use the new image.
 
 For example: