net: ip-sysctl: Add link to SCTP IPv4 scoping draft

addr_scope_policy description contains pointer to SCTP IPv4 scoping
draft but not its IETF Datatracker link. Add it.

Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250701031300.19088-6-bagasdotme@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 12c8a23..2cad74e 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -3571,7 +3571,9 @@
 	Default: 4K
 
 addr_scope_policy - INTEGER
-	Control IPv4 address scoping - draft-stewart-tsvwg-sctp-ipv4-00
+	Control IPv4 address scoping (see
+	https://datatracker.ietf.org/doc/draft-stewart-tsvwg-sctp-ipv4/00/
+	for details).
 
 	- 0   - Disable IPv4 address scoping
 	- 1   - Enable IPv4 address scoping