Note Unicode sequences in Security Considerations (#851)

Fix #837

Author: anssiko

index.bs

@@ -629,6 +629,8 @@ The API design minimizes the attack surface for the compiled computational graph
 
 Purpose-built Web APIs for measuring high-resolution time mitigate against timing attacks using techniques such as resolution reduction, adding jitter, detection of abuse and API call throttling [[hr-time-3]]. The practical deployment of WebNN implementations are likely to bring enough jitter to make timing attacks impractical (e.g. because they would use IPC) but implementers are advised to consider and test their implementations against timing attacks.
 
+Note: Security risks related to Unicode sequences are discussed in context of the {{MLOperatorOptions/label}} {{USVString}} definition.
+
 ## Guidelines for new operations ## {#security-new-ops}
 
 *This section is non-normative.*