[perl5-dbi/dbi] 79b2c9: Add cautionary note to prepare_cached docs re refs...

[Tim Bunce]

  Branch: refs/heads/master
  Home:   https://github.com/perl5-dbi/dbi
  Commit: 79b2c9ca86a65a78c3fa6d5a5b73137819db38a7
      
https://github.com/perl5-dbi/dbi/commit/79b2c9ca86a65a78c3fa6d5a5b73137819db38a7
  Author: Tim Bunce <tim.bu...@pobox.com>
  Date:   2017-08-13 (Sun, 13 Aug 2017)

  Changed paths:
    M DBI.pm

  Log Message:
  -----------
  Add cautionary note to prepare_cached docs re refs in %attr

Closes #46