Document Docker deployment for partners

https://redmine.teklia.com/issues/6934

content/deployment/architecture/cluster.mermaid

@@ -23,6 +23,7 @@ graph TD
     end
 
     subgraph server_worker1[Worker n°1]
+        direction LR
         worker[Arkindex internal worker]
         worker2[Arkindex internal worker n°2]
     end