[Perl/perl5] 94e919: POSIX.pod: Clarify mbtowc(), wctomb() pod

[Karl Williamson via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 94e919c3f7ce3a89aefc27850b210a9769c65681
      
https://github.com/Perl/perl5/commit/94e919c3f7ce3a89aefc27850b210a9769c65681
  Author: Karl Williamson <k...@cpan.org>
  Date:   2023-01-12 (Thu, 12 Jan 2023)

  Changed paths:
    M ext/POSIX/lib/POSIX.pod

  Log Message:
  -----------
  POSIX.pod: Clarify mbtowc(), wctomb() pod