[perl6/specs] 1491b9: clarify invert semantics

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/perl6/specs
  Commit: 1491b9321bf73c112c0840595f874ee740056ba4
      
https://github.com/perl6/specs/commit/1491b9321bf73c112c0840595f874ee740056ba4
  Author: TimToady <la...@wall.org>
  Date:   2015-02-27 (Fri, 27 Feb 2015)

  Changed paths:
    M S32-setting-library/Containers.pod

  Log Message:
  -----------
  clarify invert semantics