Remove notes about Google Chrome Frame from docs

Currently we don't use Google Chrome Frame anymore as support for
it will end at the end of the year.
This commit removes references to Chrome Frame within the
documentation. It is related to 2cf1ef7.

Reference #1433.
Merge branch 'master' of github.com:h5bp/html5-boilerplate into HTML5Grumpassplate

* 'master' of github.com:h5bp/html5-boilerplate:
  Remove notes about Google Chrome Frame from docs
Partials, Meta Tags, DNS Prefetching and Grunt