doc: add toLocaleString() documentatio

 - Add method description to arr.md
 - Add method use case example to cheatsheet.php

doc/arr.md

@@ -384,3 +384,23 @@ var_dump($arr->copyWithin(-2, -3, -1));
 
 ```
 
+## Return a string representing the elements in the array using a locale and timezone
+
+Default locale is en_US, and the timezone is UTC, in order to use a different locale make sure it is installed.
+
+To check available locales in linux based systems run `locale -a`
+
+To install a missing locale in linux based systems run `sudo apt-get install language-pack-XX`
+
+```php
+use HiFolks\DataType\Arr;
+
+$arr = Arr::make([1, 2, 3, 'a', 'abc', 123456.4, "2022/10/01"]);
+var_dump($arr->toLocaleString()); // Using en_US as default locale and UTC as default timezone
+// 1,2,3,a,abc,123,456.40,Sat 01 Oct 2022 12:00:00 AM UTC
+
+$arr = Arr::make([1, 2, 3, 'a', 'abc', 123456.4, "2022/10/01"]);
+var_dump($arr->toLocaleString("fr_FR.utf8", "Europe/Paris")); // Using provided locale and timezone
+// [1,2,3,a,abc,123 456,40,sam. 01 oct. 2022 00:00:00]
+```
+

examples/cheatsheet.php

@@ -271,3 +271,9 @@ function print_result(mixed $something): void
     print_result($arr->copyWithin(-2, -3, -1));
     // [1, 2, 3, 3, 4]
 }
+
+// Return a string representing the elements of the array
+$arr = Arr::make([1, 2, 3, 'a', 'abc', 123456.4, '2022/10/01']);
+
+print_r($arr->toLocaleString()); // Default locale and timezone
+print_r($arr->toLocaleString('fr_FR.utf8', 'Europe/Paris')); // Provided locale and timezone