[DOCS] Enable read-only access for kibana_system user (elastic/x-pack-elasticsearch#2465)
[DOCS] Enable read-only access for kibana_system user (elastic/x-pack-elasticsearch#2465)

Original commit: elastic/x-pack-elasticsearch@a262acb1b02d722512122fbae74c2bdd892bf616

uschindler/elasticsearch,gfyoung/elasticsearch,scorpionvicky/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,coding0011/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,gfyoung/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,HonzaKral/elasticsearch,gfyoung/elasticsearch,coding0011/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,robin13/elasticsearch,robin13/elasticsearch,coding0011/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,nknize/elasticsearch