Don't generate output if there aren't any links.

[DavidEBest]

Made the copy to results conditional - if jq isn't fed any files, then it outputs a [], which means projects without links still get a results file. This removes that case. Also, cleans up the quoting on filenames to work better with multiple files.

[ctro]

Makes sense to me, and I like using a simple if instead of trying to jigger more functionality into that already-pretty-dense jq line.