add 64-bit and hardware virtualization to requirements
add suggestion for 6GB RAM
make sure hardware virtualization is enabled in BIOS
add hint about VirtualBox host-only network setup
Windows has been tested and works!
mention VAGRANT_DEFAULT_PROVIDER
split checks into smaller functions
improve nested KVM check
improve KVM installation docs
add ssh / Windows installation docs
clarify when vagrant-libvirt fixes are required
improve bundler documentation
add pointer to vagrant-libvirt.md
keep Vagrant environment secure by default

export VAGRANT_INSECURE_PORT_FORWARDS=yes to allow access from other
hosts.