Update README.md
Merge pull request #272 from majnun/patch-1

Update README.md grammar
some README rearrangements
added link to a book in README
Fixes grammar issue in README.md
Merge pull request #278 from ktagliabue/master

Fixes small grammar issue in README file.
GPL version clarification
select a step more precisely.
Merge pull request #288 from jenil27/master

auto-resizing doesn't work when `active` class is used anythere on a page
added impress.js challenge banner
Merge remote-tracking branch 'upstream/master' into tl-press