Update: usage template

[timhallinflux]

The current usage template needs a number of updates:

• For Cloud, there are specific Flux functions which expose the limits. These limits should appear as single stat panels within the dashboard. Refer to the Flux function described here.. There is no dashboard panels which currently express.... current cardinality for an account/org and what the limits are for that org.
• The current dashboard does not include visibility into cardinality -- at all. We should review the Cardinality Now template and determine if this should be included here as well.
• We need to modify the task included in this template such that alerts are based on a cardinality limit threshold -- and not based on when a specific limit is triggered. Specifically, a task which checks for 80% of the cardinality limit.

If users wish to modify the task to provide early warnings for other limits, they can. But, the most critical example should be focused on the cardinality limit.

One of the challenges with the way that the use limits that are returned via Flux is that the result is a JSON object. This requires that it be further parsed using the json.parse() function.

A related doc issue has been filed to explain how to transform the output of the usage limits into something which is usable for dashboards, tasks, etc.

influxdata/docs-v2#3502