create-install*: use overlays to remove config duplication

Note 8.2:base is explicitly out of scope (missing rpms)

README-iso.md

@@ -32,34 +32,35 @@ Creates `install-$RELEASE.img` for input to `create-install-iso`, from:
 
 ## examples
 
-### 8.3.0
+### 8.3 updates and testing
 
 ```
 ./scripts/mirror-repos.sh 8.3
 
 sudo ./scripts/create-installimg.sh \
     --srcurl file://$HOME/mirrors/xcpng/8.3 \
-    8.3.0
+    -o install-8.3-testing.img \
+    8.3:testing
 
 ./scripts/create-install-iso.sh \
     --srcurl file://$HOME/mirrors/xcpng/8.3 \
     -V "XCP-NG_830_TEST" \
-    8.3.0 install-8.3.0-x86_64.img xcp-ng-8.3-install.iso
+    8.3:testing install-8.3-testing.img xcp-ng-8.3-testing.iso
 ```
 
-### latest 8.2
+### tip of 8.2 (8.2 + updates)
 
 ```
 ./scripts/mirror-repos.sh 8.2
 
 sudo ./scripts/create-installimg.sh \
     --srcurl file://$HOME/mirrors/xcpng/8.2 \
-    8.2.updates
+    8.2:updates
 
 ./scripts/create-install-iso.sh \
     --srcurl file://$HOME/mirrors/xcpng/8.2 \
     -V "XCP-NG_82U_TEST" \
-    8.2.updates install-8.2.updates-x86_64.img xcp-ng-8.2.updates-install.iso
+    8.2:updates install-8.2.updates-x86_64.img xcp-ng-8.2.updates-install.iso
 ```
 
 ### testing boot modes in qemu