[Perl/perl5] ee8515: perlapi: Document do_sprintf

[Karl Williamson via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: ee85153c5be6c687c46b7b967ecb852c44341f03
      
https://github.com/Perl/perl5/commit/ee85153c5be6c687c46b7b967ecb852c44341f03
  Author: Karl Williamson <k...@cpan.org>
  Date:   2022-05-20 (Fri, 20 May 2022)

  Changed paths:
    M doop.c
    M embed.fnc

  Log Message:
  -----------
  perlapi: Document do_sprintf