[boost] [type_traits] doc typo

AMDG http://boost.cvs.sourceforge.net/boost/boost/libs/type_traits/doc/type_trait... line 686 <http://boost.cvs.sourceforge.net/boost/boost/libs/type_traits/doc/type_traits.qbk?view=markup> says 684: and the second part provides the library's users with a mechanism to make the 685: above code work not only for `char`, `int` or other built-in type, 686: but for they own types as well: should be 686: but for their own types as well: In Christ, Steven Watanabe