[InterNetNews/inn] d69e71: Document libinn functions fdreserve, Fopen, Fclose

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: d69e715073e751445280a9ff43bee2cab6977799
      https://github.com/InterNetNews/inn/commit/d69e715073e751445280a9ff43bee2cab6977799
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-07-09 (Sun, 09 Jul 2023)

  Changed paths:
    M doc/pod/libinn.pod
    M include/inn/libinn.h
    M lib/reservedfd.c

  Log Message:
  -----------
  Document libinn functions fdreserve, Fopen, Fclose

see #229