Clarify error message

netbox/circuits/models/circuits.py

@@ -349,9 +349,8 @@ class CircuitTermination(
     def clean(self):
         super().clean()
 
-        # Must define either site *or* provider network
         if self.termination is None:
-            raise ValidationError(_("A circuit termination must attach to termination."))
+            raise ValidationError(_("A circuit termination must attach to a terminating object."))
 
     def save(self, *args, **kwargs):
         # Cache objects associated with the terminating object (for filtering)