Adds an xlink to the toc that points to the reconciled privileges page

As part of replacing the Elasticsearch privileges page in the Deploy and manage section with the equivalent page in the Reference section. this PR will retire the existing page in the Deploy and manage section and instead link to the correct, deduplicated page in the Reference section

Relates to #2218 and #2738

Author: yetanothertw

deploy-manage/toc.yml

@@ -608,7 +608,8 @@ toc:
                   - file: users-roles/cluster-or-deployment-auth/granting-privileges-for-data-streams-aliases.md
                   - file: users-roles/cluster-or-deployment-auth/kibana-role-management.md
                   - file: users-roles/cluster-or-deployment-auth/role-restriction.md
-              - file: users-roles/cluster-or-deployment-auth/elasticsearch-privileges.md                  
+              - title: "Elasticsearch privileges"
+                crosslink: elasticsearch://reference/elasticsearch/security-privileges.md              
               - file: users-roles/cluster-or-deployment-auth/kibana-privileges.md
               - file: users-roles/cluster-or-deployment-auth/mapping-users-groups-to-roles.md
                 children: