[perl5-dbi/dbi] c71b64: Document the new behavior for f_dir

[H.Merijn Brand]

  Branch: refs/heads/master
  Home:   https://github.com/perl5-dbi/dbi
  Commit: c71b64a678bcd708c7b75ee2bef5a360c836444c
      
https://github.com/perl5-dbi/dbi/commit/c71b64a678bcd708c7b75ee2bef5a360c836444c
  Author: H.Merijn Brand - Tux <li...@tux.freedom.nl>
  Date:   2020-10-28 (Wed, 28 Oct 2020)

  Changed paths:
    M Changes
    M DBI.pm
    M lib/DBD/File.pm

  Log Message:
  -----------
  Document the new behavior for f_dir

These changes also warrant a version increase