net: x25: remove dead links from Kconfig

Remove the "You can read more about X.25 at" links provided in
Kconfig as they have not pointed at any relevant pages for quite
a while.

An old copy of https://www.sangoma.com/tutorials/x25/ can be
retrieved via https://archive.org/web/ but nothing useful seems
to have been preserved for http://docwiki.cisco.com/wiki/X.25

For the sake of necromancy and those who really did want to
read more about X.25, a previous incarnation of Kconfig included
a link to:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios11/cbook/cx25.htm

Which can still be read at:
https://web.archive.org/web/20071013101232/http://cisco.com/en/US/docs/ios/11_0/router/configuration/guide/cx25.htmlSigned-off-by: Justin Swartz <justin.swartz@risingedge.co.za>
Acked-by: Martin Schiller <ms@dev.tdt.de>
Link: https://lore.kernel.org/r/20240306112659.25375-1-justin.swartz@risingedge.co.zaSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/x25/Kconfig

@@ -17,8 +17,6 @@ config X25
 	  if you want that) and the lower level data link layer protocol LAPB
 	  (say Y to "LAPB Data Link Driver" below if you want that).
 
-	  You can read more about X.25 at <https://www.sangoma.com/tutorials/x25/> and
-	  <http://docwiki.cisco.com/wiki/X.25>.
 	  Information about X.25 for Linux is contained in the files
 	  <file:Documentation/networking/x25.rst> and
 	  <file:Documentation/networking/x25-iface.rst>.