Template variable documentation should stop on blank lines

Consider the following template script:
```
//
// this is the template documentation
//

// this is var1 documentation
var var1 string
// this is var2 documentation
var var2 string
```

The resulting template will have:
```
Vars:
Name Type Default Value Description
var1 string //
// this is the template documentation
//

this is var1 documentation
var2 string this is var2 documentation
```

When looking backward for the variable documentation, the parser should stop on the first blank line.

The problem has been seen in Kapacitor 1.3.3.

Start by locating the template variable documentation parser and reproduce the Kapacitor 1.3.3 example from the issue. Verify that backward lookup stops at the first blank line and that the generated Vars output keeps the template and variable documentation separate.

Written by the indexing model from the issue text.