Add a license header to colormaps.py

colormaps.py

@@ -1,3 +1,17 @@
+# New matplotlib colormaps by Nathaniel J. Smith, Stefan van der Walt,
+# and (in the case of viridis) Eric Firing.
+#
+# This file and the colormaps in it are released under the CC0 license /
+# public domain dedication. We would appreciate credit if you use or
+# redistribute these colormaps, but do not impose any legal restrictions.
+#
+# To the extent possible under law, the persons who associated CC0 with
+# mpl-colormaps have waived all copyright and related or neighboring rights
+# to mpl-colormaps.
+#
+# You should have received a copy of the CC0 legalcode along with this
+# work. If not, see <http:https://creativecommons.org/publicdomain/zero/1.0/>.
+
 __all__ = ['magma', 'inferno', 'plasma', 'viridis']
 
 _magma_data = [[0.001462, 0.000466, 0.013866],