Update discovery-ec2.asciidoc

Changed recommendation from "use tribe node" to "use cross cluster search"

docs/plugins/discovery-ec2.asciidoc

@@ -223,7 +223,7 @@ Prefer https://aws.amazon.com/amazon-linux-ami/[Amazon Linux AMIs] as since Elas
 * Networking throttling takes place on smaller instance types in both the form of https://lab.getbase.com/how-we-discovered-limitations-on-the-aws-tcp-stack/[bandwidth and number of connections]. Therefore if large number of connections are needed and networking is becoming a bottleneck, avoid https://aws.amazon.com/ec2/instance-types/[instance types] with networking labeled as `Moderate` or `Low`.
 * Multicast is not supported, even when in an VPC; the aws cloud plugin which joins by performing a security group lookup.
 * When running in multiple http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html[availability zones] be sure to leverage {ref}/allocation-awareness.html[shard allocation awareness] so that not all copies of shard data reside in the same availability zone.
-* Do not span a cluster across regions.  If necessary, use a tribe node.
+* Do not span a cluster across regions.  If necessary, use cross cluster search.
 
 ===== Misc
 * If you have split your nodes into roles, consider https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Tags.html[tagging the EC2 instances] by role to make it easier to filter and view your EC2 instances in the AWS console.