Updates for using Voice iOS 4.0.0

[bobiechen-twilio]

API Changes

• CLIENT-6256 Added TVOErrorAddressIncompleteError to indicate that the number of the callee is malformed.
• CLIENT-5588 Added new state TVOCallStateReconnecting to indicate that the Call is reconnecting due to network change or lost. New callback methods call:isReconnectingWithError: and callDidReconnect: are added to the TVOCallDelegate protocol to provide state transitions.

Size Impact for 4.0.0

Architecture	App Download Size	App Storage Size
Universal	5.8 MB	12.4 MB
arm64	2.7 MB	6.7 MB
armv7	2.9 MB	5.5 MB

[bobiechen-twilio]

@piyushtank The documentation of 2.x was not migrated to gh-pages so the link does not need to be updated.