Register new Filetypes

I wanted to register two new filetypes. Unfortunately this did not work. I have created a new plugin according to these instructions

In the index.php it’s the following

Kirby::plugin('my/plugin', [
  'fileTypes' => [
    'asc' => [
      'mime' => 'application/pgp-signature',
      'type' => 'documents',
    ],
    'cer' => [
      'mime' => 'application/pkcs7-mime',
      'type' => 'documents'
    ]
  ]
]);

Which error did I make?

What exactly is the issue?

Creating new file types is one thing, but then you need a file blueprint that accepts those uploads and this file blueprint to be assigned to a files section or other upload option (files field, textarea)

Thank you,

in the blueprint default.yml I entered
accept:true
and now it works.