* Move PXE and iPXE configuration to a separate document
* Move IPMI and iSCSI configuration to a separate document
* Move bits mostly dealing with node-update to "advanced" section
* Write detailed documentation on drivers, hardware types and interfaces
* Drop outdated information, like custom DHCP file
Change-Id: I6dfc8842fb262285308578f82fab701bd29289fa
Related-Bug: #1524745