Does it run in userspace?

The new English README doesn't say it, but the Chinese one does.

> Reimplement `Zircon` microkernel in safe Rust as a userspace program!

https://github.com/rcore-os/zCore/blob/master/README.md
https://github.com/rcore-os/zCore/blob/prebuilt-2208/docs/README_LEGACY.md

