[InterNetNews/inn] 171f23: Remove ftp links in simpleftp documentation

[Russ Allbery]

  Branch: refs/heads/2.5
  Home:   https://github.com/InterNetNews/inn
  Commit: 171f23e0d1d3e6e20afe69f5d27ed20303cc3dfc
      https://github.com/InterNetNews/inn/commit/171f23e0d1d3e6e20afe69f5d27ed20303cc3dfc
  Author: Russ Allbery <eagle at eyrie.org>
  Date:   2022-07-23 (Sat, 23 Jul 2022)

  Changed paths:
    M doc/pod/simpleftp.pod

  Log Message:
  -----------
  Remove ftp links in simpleftp documentation

ftp.isc.org no longer supports the actual FTP protocol, so these
links were dead.  Mark them as verbatim text instead of links to
avoid generating dead links.