Add ChangeLog entry
diff --git a/ChangeLog b/ChangeLog
index 0eb0702..d1aacc3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 2.1.x branch released xxxx-xx-xx
+
+Changes
+   * Support TLS testing in out-of-source builds using cmake.
+
 = mbed TLS 2.1.11 branch released xxxx-xx-xx
 
 Default behavior changes