Refactor the flavor naming document to make it more readable.

Created by: garloff

Main change is to move the complex and rarely used extensions to the bottom of the document and add a section that explains why these exist at all and how they may or may not be used.

The change does not change the specification in any way, thus no new version number is assigned.

This change is in preparation of two decsisions and PRs that will be created: (1) Reduce the mandated flavors by making the flavors with disks only recommended (as discussed on May 8). (2) Discuss an alternative approach to flavor naming from PS.