docs/news: reflect EC2 image changes in the RHEL-8.5 images note

The `ami` image type was redefined based on the official RHEL EC2
images. In addition, two new image types `ec2` and `ec2-ha` were
defined. These new image types are by default not exposed via Weldr
API.

Update the docs/news/unreleased entry related to RHEL-8.5 main images to
reflect these changes.

Signed-off-by: Tomas Hozza <thozza@redhat.com>

docs/news/unreleased/rhel8.5-support.md

@@ -1,8 +1,41 @@
 # Add support for RHEL 8.5 main image types
 
 OSBuild Composer can now build RHEL 8.5 images.  The following new image types
-are supported: qcow2, vhd, vmdk, openstack, and ami
+are supported:
 
+- `qcow2`
+- `vhd`
+- `vmdk`
+- `openstack`
+- `ami`
+- `ec2`
+- `ec2-ha`
+
+## RHEL-8.5 AWS images
+
+The `ami` image type have been redefined based on the official RHEL EC2 images.
+
+Notable changes compared to RHEL-8.4 are:
+
+- the default user created by cloud-init is `ec2-user`
+- NTP client configuration uses `169.254.169.123` NTP server by default
+- the boot mode was changed from hybrid to legacy only
+
+The `ec2` and `ec2-ha` images represent the official RHEL EC2 images, which are
+produced as part of RHEL release. These contain RHUI client packages, which are
+available only from within Red Hat internal network. For this reason, these
+image types are by default not exposed via Weldr API (in the on-premise use
+case) for all RHEL releases.
+
+This default configuration can be overridden by placing the following line in
+the osbuild-composer configuration `/etc/osbuild-composer/osbuild-composer.toml`:
+
+```toml
+[weldr_api.distros."rhel-*"]
+# no lines below this section
+```
+
+## Extended osbuild support
 To support these image types, the following new types were added to support the
 functionality in osbuild.