added/updated BrowserStack link.

updated the link from 'Cross Browser Testing' to 'BrowserStack' and modified description a bit.

Author: a5hik

README.md

@@ -665,7 +665,7 @@
     + [Fullproof](http://reyesr.github.com/fullproof/)
     + [lunr.js](http://lunrjs.com/) is a simple full text search engine for your client side applications.
 + Testing
-    + [Cross Browser Testing] (http://www.browserstack.com/start) Comprehensive range of Browsers & Mobile Devices for Live Testing.
+    + [BrowserStack] (http://www.browserstack.com/start) Comprehensive range of Browsers & Mobile Emulators available online for Live Testing and ready to use.
     + [FiveUI](http://galoisinc.github.io/FiveUI/) Extensible/open browser extension & headless system for testing UI Consistency guidelines (or anything else you can test with injected JS).
     + [Writing Testable JavaScript](http://alistapart.com/article/writing-testable-javascript)
     + [Writing Testable Frontend JavaScript Part 1 – Anti-patterns and their fixes](https://shanetomlinson.com/2013/testing-javascript-frontend-part-1-anti-patterns-and-fixes/)