Add quotes to gitlab_rails[geo_node_name]

doc/user/admin_area/geo_nodes.md

@@ -16,7 +16,7 @@ All Geo nodes have the following settings:
 | Setting | Description |
 | --------| ----------- |
 | Primary | This marks a Geo Node as **primary** node. There can be only one **primary** node; make sure that you first add the **primary** node and then all the others. |
-| Name    | The unique identifier for the Geo node. Must match the setting `gitlab_rails[geo_node_name]` in `/etc/gitlab/gitlab.rb`. The setting defaults to `external_url` with a trailing slash. |
+| Name    | The unique identifier for the Geo node. Must match the setting `gitlab_rails['geo_node_name']` in `/etc/gitlab/gitlab.rb`. The setting defaults to `external_url` with a trailing slash. |
 | URL     | The instance's user-facing URL. |
 
 The node you're reading from is indicated with a green `Current node` label, and
@@ -71,7 +71,7 @@ terminated at the load balancer.
 
 In GitLab 11.11, **secondary** nodes can use identical external URLs as long as
 a unique `name` is set for each Geo node. The `gitlab.rb` setting
-`gitlab_rails[geo_node_name]` must:
+`gitlab_rails['geo_node_name']` must:
 
 - Be set for each GitLab instance that runs `unicorn`, `sidekiq`, or `geo_logcursor`.
 - Match a Geo node name.