Clarify scope for ConstraintValidators

Fix quarkusio#18763

Author: gsmet

docs/src/main/asciidoc/validation.adoc

@@ -303,7 +303,11 @@ You don't have to wire anything.
 ====
 Obviously, for each listed type, you can declare only one bean.
 
-These beans should be declared as `@ApplicationScoped`.
+Most of the time, these beans should be declared as `@ApplicationScoped`.
+
+However, in the case of ``ConstraintValidator``s that are dependent of attributes of the constraint annotation
+(typically when implementing the `initialize(A constraintAnnotation)` method),
+use the `@Dependent` scope to make sure each annotation context has a separate instance of the `ConstraintValidator` bean.
 ====
 
 ==== Constraint validators as beans