fix: next lint --report-unused-disabled-directives command

This option accepts an argument, but was not looking for one
which resulted in unexpected behavior.

packages/next/src/bin/next.ts

@@ -265,7 +265,7 @@ program
     'Prevents comments from changing config or rules.'
   )
   .option(
-    '--report-unused-disable-directives',
+    '--report-unused-disable-directives <type>',
     'Adds reported errors for unused eslint-disable directives.'
   )
   .option('--no-cache', 'Disables caching.')