Requirements are incorrect for vmware-esxi builder

[ThinGuy]

Builder fails on 22.04 due to issues with Python issues with PyYAML 5.4.1

libnbd-bin is first available in 22.04, but README.md states 18.04+ is the minimum. 18.04 and 20.04 use libnbd0. Builder also fails on 22.04 due to issues with Python during make scripts.tar.xz

Minimum RAM should be 8192 to prevent warning messages

Prereqs should be better spelled out:

18.04 & 20.04:

• build-essential
• fuse2fs
• fusefat
• libnbd0
• libvirt-daemon
• libvirt-daemon-system
• nbdfuse
• nbdkit
• ovmf
• python3-dev
• python3-pip
• qemu-block-extra
• qemu-system-x86
• qemu-utils