manpages: update xen.4 for additional authors

ARM64 has been completed.  A great deal of the recent work was done by
royger.

Author: ehem

share/man/man4/xen.4

@@ -26,7 +26,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd January 8, 2024
+.Dd January 23, 2024
 .Dt XEN 4
 .Os
 .Sh NAME
@@ -136,3 +136,9 @@ This manual page was written by
 .An Robert Watson Aq Mt rwatson@FreeBSD.org ,
 and
 .An Roger Pau Monné Aq Mt royger@FreeBSD.org .
+A great deal of work since 2015 has been done by
+.An Roger Pau Monné Aq Mt royger@FreeBSD.org .
+Initial work on adding support for DomU support on ARM64 was done by
+.An Julien Grall Aq Mt julien@xen.org .
+ARM64 DomU support was completed in 2022 by
+.An Elliott Mitchell .