[authors] Impress Guide outline updated

[Jean Hollis Weber]

I have updated the outline for the Impress Guide. Among other 
changes, it now shows the revised chapter numbers resulting from 
splitting Chapter 4 into two chapters and an appendix.

I will change the chapter numbers in the individual files, and 
the x-refs to those chapters, as I do other editing. Reviewers 
are welcome to make these changes too.

--Jean