Merge pull request #1409 from vvo/patch-2

docs(intro): remove non relevant pkg managers

intro.md

@@ -14,9 +14,8 @@ it can also be used directly in the browser.
 
 Async is also installable via:
 
+- [yarn](https://yarnpkg.com/en/): `yarn add async`
 - [bower](http://bower.io/): `bower install async`
-- [component](https://github.com/componentjs/component): `component install caolan/async`
-- [jam](http://jamjs.org/): `jam install async`
 
 Async provides around 70 functions that include the usual 'functional'
 suspects (`map`, `reduce`, `filter`, `each`…) as well as some common patterns