Doc: Update numastat.txt

The existing numactl website is no longer working.  Change website information
of numactl/libnuma utility.  And, Rearrange tab space for readability.

Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>