docs/FAQ.md: Add one about workers
This has come up a few times.
@@ -17,3 +17,9 @@ as straightforward to make any "day 2" changes to them.
In the future, it's likely the MCO will gain better support for per-node configuration
as well as tools to more easily manipulate Ignition, so there is less need to edit the
Ignition JSON directly.
+
+## Q: Why are my workers showing older versions of RHCOS?
+
+Today, the MCO only blocks on upgrades of control plane nodes. `oc get clusterversion` effectively reports the version of the control plane.
+
+To watch rollout of worker nodes, you should look at `oc describe machineconfigpool/worker` (as well as other custom pools, if any).
