fix contributing link

README.md

@@ -14,7 +14,7 @@ NB: all samples that use `getUserMedia()` must be run from a server. Calling `ge
 
 For more information about WebRTC, we maintain a list of [WebRTC Resources](https://docs.google.com/document/d/1idl_NYQhllFEFqkGQOLv8KBK8M3EVzyvxnKkHl4SuM8/edit). If you've never worked with WebRTC, we recommend you start with the 2013 Google I/O [WebRTC presentation](http://www.youtube.com/watch?v=p2HzZkd2A40).
 
-Patches and issues welcome! See [CONTRIBUTING](https://github.com/webrtc/samples/CONTRIBUTING.md) for instructions. All contributors must sign a contributor license agreement before code can be accepted. Please complete the agreement for an [individual](https://developers.google.com/open-source/cla/individual) or a [corporation](https://developers.google.com/open-source/cla/corporate) as appropriate. The [Developer's Guide](https://bit.ly/webrtcdevguide) for this repo has more information about code style, structure and validation.
+Patches and issues welcome! See [CONTRIBUTING](https://github.com/webrtc/samples/blob/master/CONTRIBUTING.md) for instructions. All contributors must sign a contributor license agreement before code can be accepted. Please complete the agreement for an [individual](https://developers.google.com/open-source/cla/individual) or a [corporation](https://developers.google.com/open-source/cla/corporate) as appropriate. The [Developer's Guide](https://bit.ly/webrtcdevguide) for this repo has more information about code style, structure and validation.
 
 ## The demos ##