Update description of filled rule

`filled` isn't really required. It just implies that it needs a value.

resources/lang/en/validation.php

@@ -41,7 +41,7 @@ return [
     'email'                => 'The :attribute must be a valid email address.',
     'exists'               => 'The selected :attribute is invalid.',
     'file'                 => 'The :attribute must be a file.',
-    'filled'               => 'The :attribute field is required.',
+    'filled'               => 'The :attribute field must have a value.',
     'image'                => 'The :attribute must be an image.',
     'in'                   => 'The selected :attribute is invalid.',
     'in_array'             => 'The :attribute field does not exist in :other.',