README.md: Update for git rename, new tiers etc.

README.md

@@ -6,34 +6,64 @@ These images are technology demonstrators, not for production use.  The intentio
 generated by the OS vendor or distribution.  Or, you can fork this repository and generate your own
 via `rpm-ostree compose image`.
 
-## Available images
+# Operating system sources
 
-### Fedora 38
+At the moment these demonstration builds use Fedora 38 and CentOS Stream 9.
 
-[registry.gitlab.com/cgwalters-playground/bootc-demo-base-images/fedora-boot:latest](https://gitlab.com/cgwalters-playground/bootc-demo-base-images/container_registry/4567470)
+# Tiers
 
+## Tier 0
 
-### CentOS Stream 9
+This is the basic tier; it has effectively just:
 
-[registry.gitlab.com/cgwalters-playground/bootc-demo-base-images/c9s-boot](https://gitlab.com/cgwalters-playground/bootc-demo-base-images/container_registry/4567470)
+- kernel systemd selinux-policy-targeted bootc
 
-## What's in them?
+You are generally going to need to generate derived images from this; installing
+it on its own will boot to a system with no automatic networking support, no SSH,
+and no default passwords etc.
 
-The [current manifest definitions](tier-1/) were forked from Fedora CoreOS, but significantly
+## Tier 1
+
+This is larger system.
+
+- NetworkManager, chrony
+- rpm-ostree (to install packages and in case it's useful "day 2")
+- openssh-server
+
+At the current time, it does not include Ignition or cloud-init; so you will
+still need to derive from it in order to inject a mechanism to log in in many
+cases.  However, it will work to install it using e.g. Anaconda and set up
+users and passwords that way.
+
+# Image matrix (Fedora)
+
+- `registry.gitlab.com/cgwalters-playground/sagano/fedora-boot-tier-0:38`
+- `registry.gitlab.com/cgwalters-playground/sagano/fedora-boot-tier-1:38`
+
+# Image matrix (CentOS Stream 9)
+
+- `registry.gitlab.com/cgwalters-playground/sagano/centos-boot-tier-0:stream9`
+- `registry.gitlab.com/cgwalters-playground/sagano/centos-boot-tier-0-rt:stream9` (realtime kernel)
+- `registry.gitlab.com/cgwalters-playground/sagano/centos-boot-tier-1:stream9`
+- `registry.gitlab.com/cgwalters-playground/sagano/centos-boot-tier-1-rt:stream9` (realtime kernel)
+
+## More about image sources
+
+The current manifest definitions [tier-0](tier-0) and [tier-1](tier-1) were forked from Fedora CoreOS, but significantly
 cut down.
 
 The existing content set is obviously subject to change and debate.
 
-Ideally, we support a workflow where even `rpm-ostree` can be removed after builds.
-
 # Building
 
 Here's an example command:
 
 ```
-$ sudo rpm-ostree compose image --authfile ~/.config/containers/myquay.json --cachedir=cache -i --format=oci fedora.yaml fedora.oci
+$ sudo rpm-ostree compose image --authfile ~/.config/containers/myquay.json --cachedir=cache -i --format=ociarchive centos-tier-0-stream9.yaml centos-tier-0-stream9.ociarchive
 ```
 
+In some situations, copying to a local `.ociarchive` file is convenient.  You can also push to a registry with `--format=registry`.
+
 More information at https://coreos.github.io/rpm-ostree/container/
 
 # Plan