edit readme

Author: freekmurze

README.md

@@ -109,13 +109,15 @@ function array_split(array $array, $numberOfPieces = 2, $preserveKeys = false)
 ```
 
 ### array_merge_values
+```php
 /**
  * Returns an array with the unique values from all the given arrays
  *
  * @param \array[] $arrays
  * @return array
  */
 function array_merge_values(array ... $arrays)
+```
 
 ## Change log