man/xl.cfg: mention not yet documented options

man/xl.cfg: mention not yet documented options

Add dummy entries for parsed but undocumented cfg file options to xl.cfg:

for i in `
grep -Ew 'xlu_cfg_get_(long|string|list|list_as_string_list)' tools/libxl/xl_cmdimpl.c | cut -f 2 -d '"' | sort -u
`
do
	grep -wq $i docs/man/xl.cfg.pod.5 || echo $i
done

current output:
acpi_s3
acpi_s4
cpus
device_model
gfx_passthru
maxmem
nodes
sched
vif2

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>