Undertone video docs (#2162)
Undertone video docs (#2162)

* Update undertone.md

Added documentation for recommended configuration settings for undertone which includes iframe based user sync

* add video object doc

Co-authored-by: Omer Koren <3e4de0e857298806edd80d409b99f28f4a276dc1@users.noreply.github.com>
prebid/prebid.github.io,prebid/prebid.github.io,prebid/prebid.github.io