Add Xrefs to the new VOP_SETLABEL(9) from mac(9) and vnode(9).

MFC after:	3 days

share/man/man9/mac.9

@@ -33,7 +33,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 25, 2015
+.Dd February 27, 2021
 .Dt MAC 9
 .Os
 .Sh NAME
@@ -162,7 +162,8 @@ for information on the MAC Framework APIs.
 .Xr ucred 9 ,
 .Xr vaccess 9 ,
 .Xr vaccess_acl_posix1e 9 ,
-.Xr VFS 9
+.Xr VFS 9 ,
+.Xr VOP_SETLABEL 9 .
 .Rs
 .%T "The FreeBSD Architecture Handbook"
 .%U "https://www.FreeBSD.org/doc/en_US.ISO8859-1/books/arch-handbook/"

share/man/man9/vnode.9

@@ -189,6 +189,7 @@ intertwining of VM Objects and Vnodes.
 .Xr VOP_REVOKE 9 ,
 .Xr VOP_SETACL 9 ,
 .Xr VOP_SETEXTATTR 9 ,
+.Xr VOP_SETLABEL 9 ,
 .Xr VOP_STRATEGY 9 ,
 .Xr VOP_VPTOCNP 9 ,
 .Xr VOP_VPTOFH 9