Add missing adapter to build snippet

examples/jsonnet-build-snippet/build-snippet.jsonnet

@@ -4,4 +4,5 @@
 { ['kube-state-metrics-' + name]: kp.kubeStateMetrics[name] for name in std.objectFields(kp.kubeStateMetrics) } +
 { ['alertmanager-' + name]: kp.alertmanager[name] for name in std.objectFields(kp.alertmanager) } +
 { ['prometheus-' + name]: kp.prometheus[name] for name in std.objectFields(kp.prometheus) } +
+{ ['prometheus-adapter-' + name]: kp.prometheusAdapter[name] for name in std.objectFields(kp.prometheusAdapter) } +
 { ['grafana-' + name]: kp.grafana[name] for name in std.objectFields(kp.grafana) }