Update README with documentation about the test-vm

README.md

@@ -25,3 +25,13 @@ EDITOR=vim agenix -d "some-secret.age" -i ~/.ssh/alex.pinwheel
 
 Or use some other SSH key that is has been used to key the secret.
 
+# Test VM
+Build the test VM with the command:
+```
+cm  --build-test-vm
+```
+
+and test it with:
+```
+cm  --run-test-vm
+```