[Geo Disaster recovery doc] fix links

doc/administration/geo/disaster_recovery/bring_primary_back.md

@@ -31,7 +31,7 @@ To bring the former primary up to date:
     the GitLab instance from scratch and setup it as a secondary node by
     following [Setup instructions][setup-geo].  In this case you don't need to follow the next step.
 
-    >**Note 2:** If you [changed the DNS records](disaster-recovery.md#step-4-optional-updating-the-primary-domains-dns-record)
+    >**Note 2:** If you [changed the DNS records](index.md#step-4-optional-updating-the-primary-domains-dns-record)
     for this node during disaster recovery procedure you may need to [block
     all the writes to this node](https://gitlab.com/gitlab-org/gitlab-ee/blob/master/doc/gitlab-geo/planned-failover.md#block-primary-traffic)
     during this procedure.