[webrtc-stats] Somewhat confusing what "This metric ... is sent by receiver" means.

taylor-b has just created a new issue for 
https://github.com/w3c/webrtc-stats:

== Somewhat confusing what "This metric ... is sent by receiver" 
means. ==
Take `firCount` as an example, which is a count of Full Intra Request 
frames. If I understand correctly:

- For an incoming RTP stream, there will be an 
`RTCInboundRTPStreamStats` where `firCount` represents the number of 
FIR frames sent by the RtpReceiver.
- For an outgoing RTP stream, there will be an 
`RTCOutboundRTPStreamStats` where `firCount` represents the number of 
FIR frames received by the RtpSender.

This wasn't immediately obvious to me. Could we instead say:

"Counts the total number of Full Intra Request (FIR) packets received 
by the `RtpSender` (if this is an `RTCOutboundRTPStreamStats`) or sent
 by the `RtpReceiver` (if this is an `RTCInboundRTPStreamStats`)"?

Or something along those lines?

Please view or discuss this issue at 
https://github.com/w3c/webrtc-stats/issues/107 using your GitHub 
account