[webrtc-pc] More simulcast examples (#2035)

aboba has just created a new issue for https://github.com/w3c/webrtc-pc:

== More simulcast examples ==
It has been suggested that we include more simulcast examples, so as to potentially uncover areas of the specification that need work. 

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/2035 using your GitHub account