docs: update sample code

The value to be validated is not necessarily a string.

Author: kenjis

user_guide_src/source/libraries/validation/034.php

@@ -2,8 +2,8 @@
 
 class MyRules
 {
-    public function even(string $str): bool
+    public function even($value): bool
     {
-        return (int) $str % 2 === 0;
+        return (int) $value % 2 === 0;
     }
 }

user_guide_src/source/libraries/validation/035.php

@@ -2,9 +2,9 @@
 
 class MyRules
 {
-    public function even(string $str, ?string &$error = null): bool
+    public function even($value, ?string &$error = null): bool
     {
-        if ((int) $str % 2 !== 0) {
+        if ((int) $value % 2 !== 0) {
             $error = lang('myerrors.evenError');
 
             return false;

user_guide_src/source/libraries/validation/037.php

@@ -2,14 +2,14 @@
 
 class MyRules
 {
-    public function required_with($str, string $fields, array $data): bool
+    public function required_with($value, string $params, array $data): bool
     {
-        $fields = explode(',', $fields);
+        $params = explode(',', $params);
 
         // If the field is present we can safely assume that
         // the field is here, no matter whether the corresponding
         // search field is present or not.
-        $present = $this->required($str ?? '');
+        $present = $this->required($value ?? '');
 
         if ($present) {
             return true;
@@ -20,7 +20,7 @@ public function required_with($str, string $fields, array $data): bool
         // as $fields is the lis
         $requiredFields = [];
 
-        foreach ($fields as $field) {
+        foreach ($params as $field) {
             if (array_key_exists($field, $data)) {
                 $requiredFields[] = $field;
             }