Fix #15331: Corrected wording in RequiredValidator::$strict [skip ci]

framework/validators/RequiredValidator.php

@@ -34,9 +34,11 @@ class RequiredValidator extends Validator
      * @var bool whether the comparison between the attribute value and [[requiredValue]] is strict.
      * When this is true, both the values and types must match.
      * Defaults to false, meaning only the values need to match.
-     * Note that when [[requiredValue]] is null, if this property is true, the validator will check
-     * if the attribute value is null; If this property is false, the validator will call [[isEmpty]]
-     * to check if the attribute value is empty.
+     *
+     * Note that behavior for when [[requiredValue]] is null is the following:
+     *
+     * - In strict mode, the validator will check if the attribute value is null
+     * - In non-strict mode validation will fail
      */
     public $strict = false;
     /**