Add an environment to the example file

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/examples/nodes/localhost.yml b/examples/nodes/localhost.yml
index 5026909..2b2612e 100644
--- a/examples/nodes/localhost.yml
+++ b/examples/nodes/localhost.yml
@@ -1,5 +1,6 @@
 classes:
   - unixnode
   - mysite
+environment: testing
 parameters:
   colour: yellow