This change documents the recently added SSD emulation feature for
IDE, SATA, and SCSI drives, which consists of:
* an `ssd` qm.conf flag [1], and
* an "SSD emulation" drive option in pve-manager. [2]
[1] https://git.proxmox.com/?p=qemu-server.git;a=commit;h=
6c875f9f315f2dc7a0a3a988622c2efdf089b171
[2] https://git.proxmox.com/?p=pve-manager.git;a=commit;h=
6e40f7b0347e4275f6bcc7a484f930d4345d1c8e
Signed-off-by: Nick Chevsky <nchevsky@gmail.com>