Update cross-cluster-search.asciidoc
Increased the required min version of CCS in the docs to 5.5
@@ -32,6 +32,9 @@ words, federated search requests will have to be sent specifically to those
nodes. Remote clusters set via the <<cluster-update-settings,cluster settings API>>
will be available on every node in the cluster.
+[WARNING]
+This feature was added as Beta in Elasticsearch `v5.3` with further improvements made in 5.4 and 5.5. It requires gateway eligible nodes to be on `v5.5` onwards.
+
The `elasticsearch.yml` config file for a _cross cluster search_ node just needs to list the
remote clusters that should be connected to, for instance:
