Fix aggregation schemas (#801)

Signed-off-by: Thomas Farr <[email protected]>

Author: Xtansia

CHANGELOG.md

@@ -102,6 +102,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Fixed CAT API schemas ([#769](https://github.com/opensearch-project/opensearch-api-specification/pull/769))
 - Fixed core API schemas ([#777](https://github.com/opensearch-project/opensearch-api-specification/pull/777))
 - Fixed Memory Circuit Breaker flaky error in ML APIs ([#788](https://github.com/opensearch-project/opensearch-api-specification/pull/788))
+- Fixed Aggregation schemas([#801](https://github.com/opensearch-project/opensearch-api-specification/pull/801))
 
 ### Changed
 - Changed `tasks._common:TaskInfo` and `tasks._common:TaskGroup` to be composed of a `tasks._common:TaskInfoBase` ([#683](https://github.com/opensearch-project/opensearch-api-specification/pull/683))