Update README.md

Removes "current limitations" link for the Chrome implementation, which was substantially out-of-date.

Author: sandersdan

README.md

@@ -1,7 +1,5 @@
 # Try it out in Chrome 86
 
-Please see [this doc for current limitations](https://docs.google.com/document/d/1H1UHn3DIw-LOfBUdNUFR6l2-zSipXuHCVmhrwF3rR6w/edit).
-
 To try it on your machine, either
 * enable `chrome://flags/#enable-experimental-web-platform-features`, or 
 * pass `--enable-blink-features=WebCodecs` flag via the command line.