README : Update the read me with a scripted aggregation alert.
README : Update the read me with a scripted aggregation alert.

Original commit: elastic/x-pack-elasticsearch@d2acb63f26bffdbcc65c3424e9f9d34561bab8a9

HonzaKral/elasticsearch,HonzaKral/elasticsearch,strapdata/elassandra,robin13/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,gfyoung/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,gfyoung/elasticsearch,vroyer/elassandra,gingerwizard/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra,vroyer/elassandra,strapdata/elassandra,robin13/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,coding0011/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,vroyer/elassandra,gfyoung/elasticsearch,nknize/elasticsearch