reword req note

Author: jrodewig

docs/reference/eql/requirements.asciidoc

@@ -36,7 +36,7 @@ mapped as a <<date,`date`>> field.
 
 [NOTE]
 ====
-You cannot use EQL to search the values of a <<nested,`nested`>> field or the
-sub-fields of a `nested` field. However, indices containing `nested` field
-mappings are otherwise supported.
+You cannot use a <<nested,`nested`>> field datatype or the sub-fields of a
+`nested` field dataype as the timestamp or event category field. See
+<<eql-nested-fields>>.
 ====