[Perl/perl5] 80f9dd: Update IO::File synopsis

[Elvin Aslanov via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 80f9dd66d1498f4eb40bcec77888c00955ed7527
      
https://github.com/Perl/perl5/commit/80f9dd66d1498f4eb40bcec77888c00955ed7527
  Author: Elvin Aslanov <rwp.prim...@gmail.com>
  Date:   2022-08-30 (Tue, 30 Aug 2022)

  Changed paths:
    M dist/IO/lib/IO/File.pm

  Log Message:
  -----------
  Update IO::File synopsis

Add `my` to examples for better practice.