[v3] Document several classes

[Benjamin Kosnik]

This looks good to me Jerry. Thanks again.

-benjamin

>Ok for 3.4, mainline?
>
>2003-01-23  Jerry Quinn  <jlquinn@optonline.net>
>
>	* include/bits/codecvt.h, include/bits/locale_facets.h,
>	include/bits/postypes.h, include/bits/stl_bvector.h,
>	include/bits/stl_multiset.h, include/bits/stl_set.h,
>	include/bits/stream_iterator.h, include/bits/streambuf_iterator.h,
>	include/std/std_complex.h:  Document.