Add printf to githost.rules

Reduce the excessive decimal places in storage space alert messages.

alerts/githost.rules

@@ -32,7 +32,7 @@ ALERT NodeFilesystemFull
   }
   ANNOTATIONS {
     summary = "Filesystem is full",
-    description = "Filesystem '{{ $labels.mountpoint }}' on {{ $labels.instance }} is full: {{ $value }}%",
+    description = "Filesystem '{{ $labels.mountpoint }}' on {{ $labels.instance }} is full: {{ $value | printf \"%.2f\" }}%",
     runbook = "troubleshooting/filesystem_alerts.md",
   }
@@ -44,7 +44,7 @@ ALERT NodeFilesystemFull
   }
   ANNOTATIONS {
     summary = "Filesystem is full",
-    description = "Filesystem '{{ $labels.mountpoint }}' on {{ $labels.instance }} is full: {{ $value }}%",
+    description = "Filesystem '{{ $labels.mountpoint }}' on {{ $labels.instance }} is full: {{ $value | printf \"%.2f\" }}%",
     runbook = "troubleshooting/filesystem_alerts.md",
   }