add copyright notice for icons and graphics (#1155)

README.md

@@ -4,3 +4,68 @@
 rviz is a 3D visualizer for the Robot Operating System (ROS) framework.
 
 For more information, please see the wiki: http://wiki.ros.org/rviz
+
+This package contains Public Domain icons downloaded from
+http://tango.freedesktop.org/releases/.
+
+Upstream Authors:				2005-2009
+
+  Ulisse Perusin <uli.peru@gmail.com>
+  Steven Garrity <sgarrity@silverorange.com>
+  Lapo Calamandrei <calamandrei@gmail.com>
+  Ryan Collier <rcollier@novell.com>
+  Rodney Dawes <dobey@novell.com>
+  Andreas Nilsson <nisses.mail@home.se>
+  Tuomas Kuosmanen <tigert@tigert.com>
+  Garrett LeSage <garrett@novell.com>
+  Jakub Steiner <jimmac@novell.com>
+
+Other icons and graphics contained in this package are released into the
+Public Domain as well.
+
+Authors:          2012 - 2017
+  David Gossow
+  Chad Rockey
+  Kei Okada
+  Julius Kammerl
+  Acorn Pooley
+
+Copyright notice [0] for all icons and graphics in this package:
+
+  | Public Domain Dedication
+  |
+  | Copyright-Only Dedication (based on United States law) or Public Domain
+  | Certification
+  |
+  | The person or persons who have associated work with this document (the
+  | "Dedicator" or "Certifier") hereby either (a) certifies that, to the best
+  | of his knowledge, the work of authorship identified is in the public
+  | domain of the country from which the work is published, or (b)
+  | hereby dedicates whatever copyright the dedicators holds in the work
+  | of authorship identified below (the "Work") to the public domain. A
+  | certifier, moreover, dedicates any copyright interest he may have in
+  | the associated work, and for these purposes, is described as a
+  | "dedicator" below.
+  |
+  | A certifier has taken reasonable steps to verify the copyright
+  | status of this work. Certifier recognizes that his good faith efforts
+  | may not shield him from liability if in fact the work certified is not
+  | in the public domain.
+  |
+  | Dedicator makes this dedication for the benefit of the public at
+  | large and to the detriment of the Dedicator's heirs and successors.
+  | Dedicator intends this dedication to be an overt act of relinquishment
+  | in perpetuity of all present and future rights under copyright law,
+  | whether vested or contingent, in the Work. Dedicator understands that
+  | such relinquishment of all rights includes the relinquishment of all
+  | rights to enforce (by lawsuit or otherwise) those copyrights in the
+  | Work.
+  |
+  | Dedicator recognizes that, once placed in the public domain, the Work
+  | may be freely reproduced, distributed, transmitted, used, modified,
+  | built upon, or otherwise exploited by anyone for any purpose, commercial
+  | or non-commercial, and in any way, including by methods that have not
+  | yet been invented or conceived.
+
+Source: http://creativecommons.org/licenses/publicdomain/
+