Remove outdated info from README (#2571)

README.md

@@ -39,15 +39,14 @@ via [npm](https://github.com/npm/npm)
 
     $ npm install sinon
 
-or via sinon's browser builds available for download on the [homepage](https://sinonjs.org/releases/). There are also [npm based CDNs](https://sinonjs.org/releases#npm-cdns) one can use.
+or via Sinon's browser builds available for download on the [homepage](https://sinonjs.org/releases/). 
+There are also [npm based CDNs](https://sinonjs.org/releases#npm-cdns) one can use.
 
 ## Usage
 
 See the [sinon project homepage](https://sinonjs.org/) for documentation on usage.
 
-If you have questions that are not covered by the documentation, you can [check out the `sinon` tag on Stack Overflow](https://stackoverflow.com/questions/tagged/sinon) or drop by <a href="irc://irc.freenode.net:6667/sinon.js">#sinon.js on irc.freenode.net:6667</a>.
-
-You can also search through the [Sinon.JS mailing list archives](http://groups.google.com/group/sinonjs).
+If you have questions that are not covered by the documentation, you can [check out the `sinon` tag on Stack Overflow](https://stackoverflow.com/questions/tagged/sinon).
 
 ## Goals