Merge pull request progit#1823 from progit/dependabot/bundler/epubche…

…ck-ruby-5.0.0.0

Update epubcheck-ruby requirement from 4.2.6.0 to 5.0.0.0

Merge pull request progit#89 from schacon/appendix-final

Appendix Final

Merge remote-tracking branch 'origin/master' into appendix

Conflicts:
	book/10-git-internals/sections/refs.asc

Merge pull request progit#43 from schacon/chapter-3-polish

Chapter 3 polish

add atlas.json and cover image