Add links and improve formatting.

Author: alvestrand

README.md

@@ -2,12 +2,12 @@
 
 (not to be confused with the MediaStreams API)
 
-This repository contains a '''proposal''' for an API that allows the
+This repository contains a **proposal** for an API that allows the
 insertion of user-defined processing steps in the pipeline that
 handles media in a WebRTC context.
 
 In order to allow such processing, it defines a number of extensions
-to the objects defined in WEBRTC-PC and MEDIACAPTURE-MAIN, and also
-draws upon definitions from WEBRTC-CODEC.
+to the objects defined in [WEBRTC-PC](https://w3c.github.io/webrtc-pc/) and [MEDIACAPTURE-MAIN](https://w3c.github.io/mediacapture-main/), and also
+draws upon definitions from [WEBRTC-CODEC](https://github.com/WICG/web-codecs).