Description of job config hints in new doc page is wrong

The 'configs' field is not a dictionary, it is actually
a list of dictionaries.  Update the description.

Closes-Bug: #1357615
Change-Id: I540abe050f1d81e36f4b5dcca547a7e5c3514c84
(cherry picked from commit 61be4ece04d6370086d8b5b9bea4224010ec0d15)