[DOCS] EQL: Add xrefs to EQL intro
[DOCS] EQL: Add xrefs to EQL intro

robin13/elasticsearch,nknize/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,nknize/elasticsearch