[DOCS] Correct over field usage for freq rare function (elastic/x-pack-elasticsearch#3435)
[DOCS] Correct over field usage for freq rare function (elastic/x-pack-elasticsearch#3435)

Original commit: elastic/x-pack-elasticsearch@2b315610b93d327e7f5473c8db9f1edc6f79e695

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