Changelog entry

Describing platform teardown and setup calls in test suites

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index 9ee82c6..d8f7425 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -93,6 +93,7 @@
    * Improve robustness of mbedtls_ssl_derive_keys against the use of
      HMAC functions with non-HMAC ciphersuites. Independently contributed
      by Jiayuan Chen in #1377. Fixes #1437.
+   * Add platform setup and teardown calls in test suites.
 
 = mbed TLS 2.8.0 branch released 2018-03-16