[stained_wood] Add textures & license attributions.

mods/materials/stained_wood/README.md

@@ -3,5 +3,23 @@
 A set of colored wood meant to replace & add to [my_door_wood][] from the
 [mydoors modpack][mydoors].
 
+### License of Textures:
+Dyed woods are derived from default_aspen_wood which is dereived from default_pine_wood.
+
+[default_aspen_wood][]:
+* Copyright [sofar][]
+* [CC BY-SA 3.0][]
+
+[default_pine_wood][]:
+* Created by [paramat][]
+* [CC BY-SA 3.0][]
+
 [mydoors]: https://forum.minetest.net/viewtopic.php?t=10626
 [my_door_wood]: https://github.com/minetest-mods/mydoors/tree/master/my_door_wood
+
+
+[default_aspen_wood]: https://github.com/minetest/minetest_game/blob/master/mods/default/textures/default_aspen_wood.png
+[default_pine_wood]: https://github.com/minetest/minetest_game/blob/master/mods/default/textures/default_pine_wood.png
+[sofar]: https://github.com/sofar
+[paramat]: https://github.com/paramat
+[CC BY-SA 3.0]: https://creativecommons.org/licenses/by-sa/3.0/legalcode