[DOCS] Updated 6.2.3 release notes
[DOCS] Updated 6.2.3 release notes

Original commit: elastic/x-pack-elasticsearch@0a549db174cfa2c043c42e9fb9d9f6784b637a6e

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