[docs] Update ripd docs on version and authentication, see bugs #261,#262

[docs] Update ripd docs on version and authentication, see bugs #261,#262

2006-05-04 Paul Jakma <paul.jakma@sun.com>

	* ripd.texi: Add Version Control as a distinct section.
	  Expand Version Control section with overview text,
	  touching on insecurity of RIPv1 and referencing
	  authentication section, cleanup text of various version
	  commands.
	  RIP Authentication: Add overview text, refer to RIPv1 version
	  control, which is required to completely secure RIP.