Update the docblock for the explode method of the Stringable class.

src/Illuminate/Support/Stringable.php

@@ -285,7 +285,7 @@ public function excerpt($phrase = '', $options = [])
     }
 
     /**
-     * Explode the string into an array.
+     * Explode the string into a collection.
      *
      * @param  string  $delimiter
      * @param  int  $limit