Warn against rm -rf'ing directory created by script

[Hailey Somerville]

alpine-chroot-install mounts several filesystems into the created chroot directory - even before it's actually chrooted into.

It appears that the destroy script takes care to unmount these filesystems before removing the chroot, however it is not immediately clear that the destroy script is the only safe way to remove the chroot.

I have just hosed a running Linux system due to making this mistake. I believe only transient state has been affected and a reboot will fix things, but a warning about this pitfall would be very much appreciated.

[Jonathan De Wachter]

Same happened to me.