howto.html: Update some links.

2003-04-24  Phil Edwards  <pme@gcc.gnu.org>

	* docs/html/17_intro/howto.html:  Update some links.
	* docs/html/18_support/howto.html:  Link doxygen numeric_limits notes.
	* docs/html/27_io/howto.html:  Link doxygen stdio_filebuf notes.
	* docs/html/ext/howto.html:  Link to demangler notes and API.
	* docs/html/faq/index.html:  Remove trailing whitespace.
	(1.4, 2.4, 3.8, 4.1):  Bring up to date.
	(5.6):  Change to a bulleted list.

	* docs/html/faq/index.txt, docs/html/documentation.html,
	docs/html/17_intro/porting.html:  Regenerate.

From-SVN: r66050