Clarify that connections to EPP should use TLS by default (kubernetes-sigs#1085)

Author: robscott

api/v1alpha2/inferencepool_types.go

@@ -95,9 +95,14 @@ type Extension struct {
 
 // ExtensionReference is a reference to the extension.
 //
+// Connections to this extension MUST use TLS by default. Implementations MAY
+// provide a way to customize this connection to use cleartext, a different
+// protocol, or custom TLS configuration.
+//
 // If a reference is invalid, the implementation MUST update the `ResolvedRefs`
-// Condition on the InferencePool's status to `status: False`. A 5XX status code MUST be returned
-// for the request that would have otherwise been routed to the invalid backend.
+// Condition on the InferencePool's status to `status: False`. A 5XX status code
+// MUST be returned for the request that would have otherwise been routed to the
+// invalid backend.
 type ExtensionReference struct {
 	// Group is the group of the referent.
 	// The default value is "", representing the Core API group.