Update SIP documentation

Hello,

I'm working with the SIP driver in a project, I noticed that the documentation about the SIP driver is out-dated (http://dev.iridiummobile.net/SIP-telephony/en). Can you please update this to include an explanation of all the available properties. In particular the last ones (Echo Cancellation, Volume Control, Noise Suppression, Activation By Voice, Use Decline)

Current documentation:

Latest version of i3 Pro: