[perl6/specs] 469332: Document new features of is()/isnt()

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/perl6/specs
  Commit: 469332388b368d42fd59dcab031c9666760a2777
      
https://github.com/perl6/specs/commit/469332388b368d42fd59dcab031c9666760a2777
  Author: Elizabeth Mattijsen <l...@dijkmat.nl>
  Date:   2015-02-25 (Wed, 25 Feb 2015)

  Changed paths:
    M S24-testing.pod

  Log Message:
  -----------
  Document new features of is()/isnt()