[InterNetNews/inn] 6926b5: Improve documentation of an overview rebuild

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: 6926b5c0f209e0397c436f4a835a0ff02cfc2ebf
      https://github.com/InterNetNews/inn/commit/6926b5c0f209e0397c436f4a835a0ff02cfc2ebf
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2022-09-10 (Sat, 10 Sep 2022)

  Changed paths:
    M doc/pod/makehistory.pod

  Log Message:
  -----------
  Improve documentation of an overview rebuild

Mention the buffindexed buffers to create (when using that method) and the
fact that there may be error logs during the rebuild for articles whose
generated overview data exceed the internal limit in size of makehistory
(using QIO).