[InterNetNews/inn] c5ce9b: Document the exclusion of control groups in newsfeeds

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: c5ce9b84e690f00b7911986760e3450c69324b82
      https://github.com/InterNetNews/inn/commit/c5ce9b84e690f00b7911986760e3450c69324b82
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2022-02-05 (Sat, 05 Feb 2022)

  Changed paths:
    M doc/pod/newsfeeds.pod

  Log Message:
  -----------
  Document the exclusion of control groups in newsfeeds

Mention it in a second example at the beginning of the man page,
as it is a common use case.