Documentation: provide better user experience with autorefreshing grafana dashboard

Documentation/etcd-mixin/mixin.libsonnet

@@ -1263,7 +1263,7 @@
       annotations: {
         list: [],
       },
-      refresh: false,
+      refresh: '10s',
       schemaVersion: 13,
       version: 215,
       links: [],

Documentation/op-guide/grafana.json

@@ -13,7 +13,7 @@
         "links": [
 
         ],
-        "refresh": false,
+        "refresh": "10s",
         "rows": [
             {
                 "collapse": false,