adding updated chapter 13 RMD file
adding updated chapter 13 RMD file
adding updated chapter 13 RMD, .Md, .HTML file(s)
adding updated chapter 13 RMD, .Md, .HTML file(s)
Merge pull request #6 from swihart/master

figure 13.1, 13.1x in their .rmd, .md, and html glory