Add ChangeLog entry about listing all SAN

Add a ChangeLog entry that indicates that all SAN types are
now listed in the corresponding certificate field.
diff --git a/ChangeLog b/ChangeLog
index f6763fc..959904a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,8 @@
    * Add support for parsing certificate policies extension, as defined in
      RFC 5280 section 4.2.1.4. Currently, only the "Any Policy" policy is
      supported.
+   * List all SAN types in the subject_alt_names field of the certificate.
+     Resolves #459.
 
 Bugfix
    * Fix private key DER output in the key_app_writer example. File contents