Since commit 6cd046c501 ("xen/arm: Enlarge identity map space to 10TB")
Xen can be loaded below 10 TiB. Update docs accordingly.
Take the opportunity to update stale links to Linux docs.
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>