Add language entry for starts_with rule

See laravel/framework#26612

Author: driesvints

resources/lang/en/validation.php

@@ -108,6 +108,7 @@
         'string' => 'The :attribute must be :size characters.',
         'array' => 'The :attribute must contain :size items.',
     ],
+    'starts_with' => 'The :attribute must start with one of the following: :values',
     'string' => 'The :attribute must be a string.',
     'timezone' => 'The :attribute must be a valid zone.',
     'unique' => 'The :attribute has already been taken.',