added Appliance disaster recovery pages to sidebar
added Appliance disaster recovery pages to sidebar

/appliance/disaster-recovery and /appliance/disaster-recovery-raci were missing.
Besides, we prefer geo-ha disaster recovery to be accessible only under get-ha node.
jeffreylees/docs,auth0/docs,yvonnewilson/docs,auth0/docs,jeffreylees/docs,jeffreylees/docs,yvonnewilson/docs,auth0/docs,yvonnewilson/docs