[DOCS] Fixed title in 6.1.0 release notes
[DOCS] Fixed title in 6.1.0 release notes

Original commit: elastic/x-pack-elasticsearch@2ea38221f4226745511d07477ea46d0a797d4171

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