Document each node and chain method with explicit data examples

Nobody has claimed this yet.

It would be extremely useful if the documentation for each Kapacitor node and chain method included explicit example input data and the resulting output data in Influx line format or tabular format. Sometimes it's not very clear from the documentation what the result of applying a given method or node would be just from reading the description.

For example, the [join node](https://docs.influxdata.com/kapacitor/v1.3/nodes/join_node/) might have a blurb like:

# Inputs

## Measurement ``error``

```
time value
---- ------
1508860350607742142 10
1508860351607742142 11
```

## Measurement ``requests``

```
time value
---- ------
1508860350607742142 12
1508860351607742142 13
```

# Outputs

```
time error.value requests.value
---- ----------- --------------
1508860350607742142 10 12
1508860351607742142 11 13
```

Start with the join node documentation page linked in the issue and review how node and chain method pages are organized. Inventory the relevant documentation pages, then add explicit input and output examples in Influx line or tabular format for each. The work is done when every node and chain method has an example that makes its resulting data clear.

Written by the indexing model from the issue text.