Make README reflect the changed release strategy

README.md

@@ -6,12 +6,11 @@ Administration Visualized](https://nav.uninett.no/) virtual appliance, using
 
 ## Building
 
-Appliances are built automatically by GitHub workflows in this
-repository. Check the
-[Releases](https://github.com/Uninett/navappliance/releases) page of the
-repository for the latest build (the release date may currently be fixed,
-though the contents of that release may be updated along the way).  To build an
-appliance manually, run the `build.sh` script.
+Appliances are built automatically by GitHub workflows in this repository.
+Successful builds are tagged and published as releases.  Check the [Releases
+page](https://github.com/Uninett/navappliance/releases) for the latest build.
+
+To build an appliance manually, run the `build.sh` script.
 
 ## Booting the appliance for the first time