Update AUTHORS.txt

Author: davidzhao

AUTHORS.txt

@@ -51,6 +51,7 @@ Clayton McCray <cpmdmccray@gmail.com>
 cnderrauber <zengjie9004@gmail.com>
 cyannuk <cyannuk@issart.com>
 Daniele Sluijters <daenney@users.noreply.github.com>
+David <dz@livekit.io>
 David Hamilton <davidhamiltron@gmail.com>
 David Zhao <david@davidzhao.com>
 David Zhao <dz@livekit.io>