update example with new syntax

Signed-off-by: Jan Willies <jan.willies@accenture.com>

pkg/env/data.go

@@ -26,10 +26,11 @@ const (
 var DefaultOverrideData = []byte(`local base = import "base.libsonnet";
 // uncomment if you reference ksonnet-lib
 // local k = import "k.libsonnet";
+// local deployment = k.apps.v1beta2.deployment;
 
 base + {
   // Insert user-specified overrides here. For example if a component is named \"nginx-deployment\", you might have something like:\n")
-  // "nginx-deployment"+: k.deployment.mixin.metadata.labels({foo: "bar"})
+  // "nginx-deployment"+: deployment.mixin.metadata.withLabels({foo: "bar"})
 }
 `)