Doc Rework: Section 9.16.13 SQL/JSON Query Functions

Hey!

Lots of SQL/JSON threads going about.  This one is less about technical correctness and more about usability of the documentation.  Though in writing this I am finding some things that aren't quite clear.  I'm going to come back with those on a follow-on post once I get a chance to make my second pass on this.  But for the moment just opening it up to a content and structure review.

Please focus on the text changes.  It passes "check-docs" but I still need to work on layout and stuff in html (markup, some more links).

Thanks!

David J.

p.s. v1 exists here (is just the idea of using basically variable names in the function signature and minimizing direct syntax in the table);