bash-completion: add some architectures.
bash-completion: add some architectures.

According to the runtime-spec, the values which can be accept by --arch
are listed in the Go Language document for $GOARCH.

Signed-off-by: Zhai Zhaoxuan <0622d86d857a1512011361653affaa270f214497@cn.fujitsu.com>

liangchenye/ocitools,opencontainers/ocitools,liangchenye/ocitools,opencontainers/runtime-tools,opencontainers/runtime-tools,wking/ocitools-v2,opencontainers/ocitools,wking/ocitools-v2