[doc] minor tweaks, refine ospf redist,passive-inter, and abr-type help

[doc] minor tweaks, refine ospf redist,passive-inter, and abr-type help

2006-07-27 Paul Jakma <paul.jakma@sun.com>

	* quagga.texi: Remove unused index definitions
	  Add an Index node - for the concept index.
	* routeserver.texi: Set exampleindex to 0, so the example configs
	  with long IPv6 addresses stand better chance of fitting.
	* overview.texi: 'Supported RFC' -> 'Supported RFCs'
	  Remove paragraph indentation - texinfo does that.
	  Revise the supported OS list slightly.
	  Remove the IPv6 stack list, seems very dated and irrelevant.
	  Revise the 'How to get Quagga' section.
	* ospfd.texi: minor tweaks: add some anchors, fix some minor
	  format issues.
	  Revise the help for 'abr-type'.
	  Note that text authentication is unwise, recc'd MD5.
	  Add some extra text for redistribute and passive-interface,
	  about how latter can substitute for redist connected.