Updated Valid constraint reference

| Q              | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets | 

Revised PR #4351 for 2.3 branch
I think this is wrong, this sentence is about option ``deep``.
Constraint can be **applied** to property, but not enabled and option ``deep`` can be **enabled**.