Doc: Mark 'ReleaseDate' property as required
Doc: Mark 'ReleaseDate' property as required

Task-number: QTIFW-223

Change-Id: Ic4ac3d32f4754294dcd12a309a3a86db9a6ff578
Reviewed-by: Niels Weber <df24410c43e1f71d7f720aa26e4fcb77ce70f242@digia.com>

olear/qtifw,olear/qtifw,olear/qtifw,olear/qtifw