FAQ: AWS private regions

This has come up a few times.

FAQ.md

@@ -96,3 +96,19 @@ While this can be helpful for short-term fixes, it is important to remember that
 is in place, as the cluster currently has [no mechanism for reporting](https://github.com/openshift/machine-config-operator/issues/945) that the node has been changed in this
 fashion.  This kind of package replacement can also leave your nodes exposed to potential problems
 that are fixed in newer versions of the package.
+
+## Q: How do I get RHCOS in a private EC2 region?
+
+The RHCOS pipeline uploads to most public EC2 regions, but there are some private regions.
+
+In order to create an AMI in one of these regions, you will need to download the VMDK, upload it to S3 in your target region, and then use [AWS vm-import](https://aws.amazon.com/ec2/vm-import/).
+
+See [the RHCOS build information](https://github.com/openshift/installer/blob/46f909e4ccb4f7a4f82bf1ee28b32fa011a6bd1f/data/data/rhcos.json#L64) pinned in the installer for the snapshot for a given OpenShift release.
+
+Combine the `baseURI` and `images/aws/path` entries in the build JSON to download the snapshot:
+
+```
+$ curl -LO https://releases-art-rhcos.svc.ci.openshift.org/art/storage/releases/rhcos-4.2/42.80.20191002.0/rhcos-42.80.20191002.0-aws.vmdk
+```
+
+Upload it to an S3 location, then follow the instructions for [importing an image](https://docs.aws.amazon.com/vm-import/latest/userguide/vmimport-image-import.html).