[class.expl.init] Fix sample for copy-list-initialization

Fix comment stating a copy operation of temporary occurs at a
copy-list-initialization expression, potentially misleading correct
interpretation of list-initialization rules.

For background discussion see
http://stackoverflow.com/q/13693871/1000282
Merge pull request #37 from oblitum/copy-list-initialization-sample-fix

[class.expl.init] Fix sample for copy-list-initialization