Update validation.md (#9075)

* Update validation.md

* Update validation.md

---------

Co-authored-by: Taylor Otwell <[email protected]>

Author: coendr

validation.md

@@ -941,6 +941,7 @@ Below is a list of all available validation rules and their function:
 [Regular Expression](#rule-regex)
 [Required](#rule-required)
 [Required If](#rule-required-if)
+[Required If Accepted](#rule-required-if-accepted)
 [Required Unless](#rule-required-unless)
 [Required With](#rule-required-with)
 [Required With All](#rule-required-with-all)
@@ -1664,6 +1665,11 @@ If you would like to construct a more complex condition for the `required_if` ru
         'role_id' => Rule::requiredIf(fn () => $request->user()->is_admin),
     ]);
 
+<a name="rule-required-if-accepted"></a>
+#### required_if_accepted:_anotherfield,...
+
+The field under validation must be present and not empty if the _anotherfield_ field is equal to `yes`, `on`, `1`, `"1"`, `true`, or `"true"`.
+
 <a name="rule-required-unless"></a>
 #### required_unless:_anotherfield_,_value_,...