[DOCS] Small fixes in the overall buckets API (elastic/x-pack-elasticsearch#2732)
[DOCS] Small fixes in the overall buckets API (elastic/x-pack-elasticsearch#2732)

* [DOCS] Small fixes in the overall buckets API

* [DOCS] Addressed feedback in overall buckets API

Original commit: elastic/x-pack-elasticsearch@6aaa2a54cac40e4830fa91abb312e35d8bff617a

vroyer/elassandra,vroyer/elassandra,vroyer/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra