Merge branch 'deploykeys-api-doc' into 'master'

Document admin access requirement for /deploy_keys endpoint

Closes #23807

See merge request !7164

doc/api/deploy_keys.md

@@ -2,7 +2,7 @@
 
 ## List all deploy keys
 
-Get a list of all deploy keys across all projects.
+Get a list of all deploy keys across all projects of the GitLab instance. This endpoint requires admin access.
 
 ```
 GET /deploy_keys