Rename Prometheus alerts for consistency

Change-Id: I2c2ba23b7ae63d4343db374f4429574ac9c1f5e3
diff --git a/docker/meta/prometheus.yml b/docker/meta/prometheus.yml
index a84ad0e..14a6f1a 100644
--- a/docker/meta/prometheus.yml
+++ b/docker/meta/prometheus.yml
@@ -3,7 +3,7 @@
 server:
   alert:
 {%- if host.get('enabled') %}
-    ProcstatRunningDockerd:
+    DockerdProcessDown:
       if: >-
         procstat_running{process_name="dockerd"} == 0
   {%- raw %}