Update ChangeLog style

Add dot at end of change in ChangeLog
diff --git a/ChangeLog b/ChangeLog
index f13982b..2f17367 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,7 +4,7 @@
 
 Features
    * Allow comments in test data files.
-   * Add support for public keys encoded in PKCS#1 format
+   * Add support for public keys encoded in PKCS#1 format.
 
 Bugfix
    * Fix memory leak in mbedtls_ssl_set_hostname() when called multiple times.