corosync-2.4.0 is out together with man pages. You can find them ether in corosync-qnetd and corosync-qdevice packages or directly in upstream github:
pcs-0.9.152-3.el7 with qdevice support is now available. You may take a look at bz1158805 comment 17 to see how to manage qdevice using pcs. New pcs commands are of course covered by pcs man page and built-in help.
Re-opening this for 7.4 because quorum devices were in technical preview for 7.3 and once we verify that they are fully supported for 7.4 I will need to update the document.