Update cypher-shell.adoc

Author: loveleif

modules/ROOT/pages/tools/cypher-shell.adoc

@@ -409,6 +409,7 @@ type example.cypher | bin/cypher-shell.bat -u neo4j -p <password> --format plain
 
 Cypher Shell supports querying based on parameters.
 Use `:param <Cypher Map>` to set parameters or the older arrow syntax `:param name => <Cypher Expression>`.
+When using the arrow syntax, expressions are restricted to a single line.
 List current parameters with `:param`.
 Clear parameters with `:param clear`.