[DOCS] Add release notes script that merges two repos
[DOCS] Add release notes script that merges two repos

Original commit: elastic/x-pack-elasticsearch@4ae49add11fca47bee4f459d2ba5e82790a38788

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