Add fix and credit for #742 to the ChangeLog

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index f81687b..7399cad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -51,6 +51,9 @@
      by missing calls to mbedtls_pem_free() in cases when a
      MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT error was encountered. Found and
      fix proposed by Guido Vranken. #722
+   * Fixed the templates used to generate project and solution files for Visual
+     Studio 2015 as well as the files themselves, to remove a build warning
+     generated in Visual Studio 2015. Reported by Steve Valliere. #742
 
 = mbed TLS 2.4.1 branch released 2016-12-13