[ttml2] Update acknowledgments.

skynavga has just created a new issue for https://github.com/w3c/ttml2:

== Update acknowledgments. ==
 + add Stefan Pöschel

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/901 using your GitHub account

Received on Sunday, 15 July 2018 13:59:15 UTC