[packagechooser] Use overrides on AppData for example

src/modules/packagechooser/packagechooser.conf

@@ -54,6 +54,12 @@ mode: required
 # (from AppData name), description (from AppData description paragraphs
 # or the summary entries), and a screenshot (the defautl screenshot
 # from AppData). No package is set (but that is unused anyway).
+#
+# AppData may contain IDs that are not useful inside Calamares,
+# and the screenshot URL may be remote -- a remote URL will not
+# be loaded and the screenshot will be missing. An item with *appdata*
+# **may** specify an ID or screenshot path, as above. This will override
+# the settings from AppData.
 items:
     - id: ""
       package: ""
@@ -72,5 +78,7 @@ items:
       name: GNOME
       description: GNU Networked Object Modeling Environment Desktop
       screenshot: ":/images/gnome.png"
-    - appdata: ../io.calamares.calamares.appdata.xml
+    - id: calamares
+      appdata: ../io.calamares.calamares.appdata.xml
+      screenshot: ":/images/calamares.png"
 

src/modules/packagechooser/packagechooser.qrc

@@ -3,5 +3,6 @@
         <file>images/no-selection.png</file>
         <file>images/kde.png</file>
         <file>images/gnome.png</file>
+        <file>images/calamares.png</file>
     </qresource>
 </RCC>