landlock: Document fs.resolve_unix audit blocker

The Landlock audit code can emit fs.resolve_unix as a filesystem blocker
for pathname UNIX socket resolution denials, but the admin guide's
blockers list did not mention it.

Add the missing blocker name and ABI version to keep the audit
documentation in sync with the emitted records.

Fixes: ae97330d1b ("landlock: Control pathname UNIX domain socket resolution by path")
Signed-off-by: Doehyun Baek <doehyunbaek@gmail.com>
Reviewed-by: Günther Noack <gnoack@google.com>
[mic: Fix subject]
Link: https://patch.msgid.link/20260625092819.1870049-1-doehyunbaek@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Documentation/admin-guide/LSM/landlock.rst

@@ -52,6 +52,7 @@ AUDIT_LANDLOCK_ACCESS
         - fs.refer (ABI 2+)
         - fs.truncate (ABI 3+)
         - fs.ioctl_dev (ABI 5+)
+        - fs.resolve_unix (ABI 9+)
 
     **net.*** - Network access rights (ABI 4+):
         - net.bind_tcp - TCP port binding was denied