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
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
Typo

:)
Merge pull request #300 from DronRathore/readme.md---typo

Typo in README
end of challenge