Misc: Mac OS is now OS X, thanks @xfq

Closes gh-1970

README.md

@@ -25,7 +25,7 @@ In order to build jQuery, you need to have the latest Node.js/npm and git 1.7 or
 
 For Windows, you have to download and install [git](http://git-scm.com/downloads) and [Node.js](http://nodejs.org/download/).
 
-Mac OS users should install [Homebrew](http://brew.sh/). Once Homebrew is installed, run `brew install git` to install git,
+OS X users should install [Homebrew](http://brew.sh/). Once Homebrew is installed, run `brew install git` to install git,
 and `brew install node` to install Node.js.
 
 Linux/BSD users should use their appropriate package managers to install git and Node.js, or build from source