doc: fix Linux guide for arm64 cross-compilation

doc: fix Linux guide for arm64 cross-compilation

libnuma.so is needed to augment the cross toolchain with NUMA support.
This fixed meson cross compiling issue.

Command used:
meson arm64-build --cross-file config/arm/arm64_armv8_linux_gcc
ninja -C arm64-build

Compiling error:
.../aarch64-linux-gnu/bin/ld: lib/librte_eal.so.10.1: version node
not found for symbol numa_run_on_node_mask@@libnuma_1.2
.../aarch64-linux-gnu/bin/ld: failed to set dynamic section sizes:
Bad value
collect2: error: ld returned 1 exit status
[58/1370] Compiling C object 'lib/76b5a35@@rte_cmdline@sta/
librte_cmdline_cmdline_parse_string.c.o'.
ninja: build stopped: subcommand failed.

Fixes: 01add9da25cd ("doc: add cross compiling guide")
Cc: stable@dpdk.org
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>