Update README.md and fix int4 matmul example
Signed-off-by:Gian Marco Iodice <gianmarco.iodice@arm.com> Approved-by:
Viet-Hoa Do <viet-hoa.do@arm.com>
Signed-off-by:Gian Marco Iodice <gianmarco.iodice@arm.com> Approved-by:
Viet-Hoa Do <viet-hoa.do@arm.com>