feat: add mailto showcase to the emails definition

          This is the first inject.

          It is multiline and contains a file.

          Clicking on <a href="mailto:test@mail.ex">this link</a> will open the email form. The test@mail.ex address will be set as the recipient.

          This also works: <test@mail.ex>.

        file_name: file1.txt

      overlay: { duration: 1 }