Add the "Git excludes" step to the overview, the sample plan, the numbered
run steps and a new section: which paths are excluded and why, that nothing
is committed or changed in a tracked file, that the entries live in
.git/info/exclude and so are not shared with a clone, what happens to a path
git already tracks, and how to track one anyway. Add the tracked-path case to
the error table and the new roles of git.sh and framework.sh to the code
layout.
Closes#67
Tirsvad