update OCIO configs

Author: devernay

OpenColorIO-Configs-README.md

@@ -2,5 +2,5 @@ As mentionned in the INSTALL files, the default OpenColorIO
 configuration files must be downloaded and unpacked at the root of the
 Natron source tree, using something like:
 
-    curl -k -L https://github.com/MrKepzie/OpenColorIO-Configs/archive/Natron-v2.0.tar.gz | tar zxf -
-    mv OpenColorIO-Configs-Natron-v2.0 OpenColorIO-Configs
+    curl -k -L https://github.com/MrKepzie/OpenColorIO-Configs/archive/Natron-v2.1.tar.gz | tar zxf -
+    mv OpenColorIO-Configs-Natron-v2.1 OpenColorIO-Configs