manifests: Add descriptions

This is generally useful for the same reason dpkg/rpm packages
have descriptions. But it's also specifically preparation
for the base image builder having a list operation to show
available configurations.

Signed-off-by: Colin Walters <walters@verbum.org>

minimal/manifest.yaml

@@ -1,3 +1,6 @@
+metadata:
+  summary: Effectively just bootc, systemd, kernel, and dnf as a starting point.
+
 edition: "2024"
 
 # Be minimal

tier-1/manifest.yaml

@@ -1,3 +1,9 @@
+metadata:
+  summary: |
+    A relatively full, but still generic base image. Roughly
+    similar to a headless server installation. Automatic updates
+    are on by default.
+
 # Flip this back on, we're going to be a larger system
 recommends: true
 

tier-x/manifest.yaml

@@ -1,3 +1,11 @@
+metadata:
+  summary: |
+    A relatively full, but still generic base image. Roughly
+    similar to a smaller Fedora CoreOS. Includes NetworkManager,
+    openssh, various CLI tools, etc.
+    
+    Automatic updates are not on by default.
+
 include:
   - ../minimal/manifest.yaml