[InterNetNews/inn] 85cc3c: Show metadata in OVERVIEW.FMT to NNTPv2 clients

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: 85cc3c205d072e94ab64cc0fd364321e30fc7451
      https://github.com/InterNetNews/inn/commit/85cc3c205d072e94ab64cc0fd364321e30fc7451
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-03-18 (Sat, 18 Mar 2023)

  Changed paths:
    M doc/pod/news.pod
    M nnrpd/list.c
    M nnrpd/nnrpd.c
    M nnrpd/nnrpd.h

  Log Message:
  -----------
  Show metadata in OVERVIEW.FMT to NNTPv2 clients

slrn 1.0.3 fails to parse ":bytes" and ":lines" in LIST OVERVIEW.FMT
responses, with the error:

OVERVIEW.FMT not RFC 2980 compliant -- XOVER support disabled.

These metadata items will now be shown only if the news reader has
previously used CAPABILITIES in the session.  Otherwise, legacy
"Bytes:" and "Lines:" are shown.