Add ChangeLog entry about license change
diff --git a/ChangeLog b/ChangeLog
index 5f50915..d3636f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,7 +3,8 @@
 = mbed TLS 2.1.0 released 2015-09-04
 
 Features
-   * Added support for yotta as a build system
+   * Added support for yotta as a build system.
+   * Primary open source license changed to Apache 2.0 license.
 
 Bugfix
    * Fix segfault in the benchmark program when benchmarking DHM.