Add disk usage_percent layout

canned/disk.json

@@ -0,0 +1,19 @@
+ {
+    "id": "0b75be4e-3454-4d5d-9a98-ca77c81397f6",
+ 	"measurement": "disk",
+ 	"app": "Host disk metrics",
+ 	"cells": [{
+ 		"x": 0,
+ 		"y": 0,
+ 		"w": 10,
+ 		"h": 10,
+        "i": "5825a4dd-df97-4e99-a99d-67b68833c183",
+        "name": "disk ",
+ 		"queries": [{
+ 			"query": "select used_percent from disk",
+ 			"db": "telegraf",
+ 			"rp": "autogen",
+  			"groupbys": ["path"]
+		}]
+ 	}]
+ }