Add instructions on how to use docker kernel and qemu
Add instructions on how to use docker kernel and qemu

This allows someone to just use the kernel and qemu we build for tests
without having to deal with version differences.

Signed-off-by: Gan Shun Lim <2e7f5e6c120ad45644b6c32fd10bafcf8f554f9f@gmail.com>

hugelgupf/u-root,hugelgupf/u-root,u-root/u-root,hugelgupf/u-root,u-root/u-root,u-root/u-root,hugelgupf/u-root