[DOCS] Formatted roles API (elastic/x-pack-elasticsearch#2577)
[DOCS] Formatted roles API (elastic/x-pack-elasticsearch#2577)

* [DOCS] Formatted roles API

* [DOCS] Addressed feedback about roles API

Original commit: elastic/x-pack-elasticsearch@414d06bc13734b88fb4a58a5333fbb367709ff28

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