Update README.md to point to LICENSE.md

Erroneously referred to COPYRIGHT.md
diff --git a/README.md b/README.md
index 43c6e85..e23d009 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@
 ## License
 This work is released as open source under a Apache-style license from Khronos including a Khronos copyright.
 
-See COPYRIGHT.txt for a full list of licenses used in this repository.
+See LICENSE.txt for a full list of licenses used in this repository.
 
 ## Acknowledgements
 While this project has been developed primarily by LunarG, Inc., there are many other