Add ChangeLog entry for new extensions change

Add an entry for the new x509 extension parsing support.
diff --git a/ChangeLog b/ChangeLog
index 58ff147..ce50950 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -61,6 +61,10 @@
    * Add MBEDTLS_REMOVE_3DES_CIPHERSUITES to allow removing 3DES ciphersuites
      from the default list (enabled by default). See
      https://sweet32.info/SWEET32_CCS16.pdf.
+   * Add support for parsing subject alternative name, of type otherName,
+     HardwareModuleName, as defined in rfc 4108 section 5.
+   * Add support for parsing certificate policies extension, as defined in
+     rfc 5280 section 4.2.1.4. Currently only supports "Any Policy" policy.
 
 API Changes
    * Add a new X.509 API call `mbedtls_x509_parse_der_nocopy()`.