[DOCS] EQL: Note CCS is not supported (#72975)

docs/reference/eql/syntax.asciidoc

@@ -826,6 +826,13 @@ You cannot use EQL to search the values of a <<nested,`nested`>> field or the
 sub-fields of a `nested` field. However, data streams and indices containing
 `nested` field mappings are otherwise supported.
 
+[discrete]
+[[eql-ccs-support]]
+==== {ccs-cap} is not supported
+
+EQL search APIs do not support <<modules-cross-cluster-search,{ccs}
+({ccs-init})>>.
+
 [discrete]
 [[eql-unsupported-syntax]]
 ==== Differences from Endgame EQL syntax