Create risk-grid-12.txt

This is a continuation of the risk grid that:
- makes a first attempt to reorder the issues based on their granularity - highest first and;
- adds the issue title to the issue number for ease of navigation and;
- merges the Commentary and Comments fields to reduce redundancy.

This version removes issue numbers because the titles replace the numbering, and it avoids long term issues with quotations of different issue numbers across different versions of the risk grid.

Author: shanecoughlan