update trigger_agent w/ valid example

[fredericrous]

This simple change could make the example more accurate and therefore help new comers .
I just lost 30min not understanding why the agent wasn't working thinking it was due to my regex

[dsander]

Hmm that should not make any difference, as far as I know the leading $. is optional:

[1] pry(main)> Utils.value_at({'data' => 'test'}, 'data')
=> "test"
[2] pry(main)> Utils.value_at({'data' => 'test'}, '$.data')
=> "test"

Do you still remember what kind of problem you had with a JSONPath expression that did not have the leading $.?