[DOCS] reverse-nested aggs are added in 1.2.0

docs/reference/search/aggregations/bucket/reverse-nested-aggregation.asciidoc

@@ -1,6 +1,8 @@
 [[search-aggregations-bucket-reverse-nested-aggregation]]
 === Reverse nested Aggregation
 
+added[1.2.0]
+
 A special single bucket aggregation that enables aggregating on parent docs from nested documents. Effectively this
 aggregation can break out of the nested block structure and link to other nested structures or the root document,
 which allows nesting other aggregations that aren't part of the nested object in a nested aggregation.