Change prometheus job name to Pi-Hosted (#232)

configs/prometheus.yml

@@ -1,5 +1,5 @@
 scrape_configs:
-  - job_name: 'prometheus'
+  - job_name: 'Pi-Hosted'
     scrape_interval: 30s
     static_configs:
       - targets: ['localhost:9090', 'cadvisor:8080', 'node-exporter:9100']