added a section on model selection using bfastpp

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bfast@467 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
added a section on model selection using bfastpp

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/bfast@468 edb9625f-4e0d-4859-8d74-9fd3b1da38cb