If there are parts that specifically you'd want to have better documentation for, please let me know here.

Generally we've been moving command line towards a scheme where each option describes an aspect of either the guest (a device, the board type, the CPU model) or the interface to the host (a file holding the contents of the disk, the network bridge to attach to, how to show graphic contents), with some options providing both as a shortcut (for example -nic, -audio, -serial).