Documentation error in `mbedtls_ssl_get_session`

Fix Documentation error in `mbedtls_ssl_get_session`.
This function supports deep copying of the session,
and the peer certificate is not lost anymore, Resolves #926
diff --git a/ChangeLog b/ChangeLog
index 44533d2..10f0773 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,9 @@
      return value. Found by @davidwu2000. #839
    * Fix a memory leak in mbedtls_x509_csr_parse(), found by catenacyber,
      Philippe Antoine. Fixes #1623.
+   * Remove wrong documentation for `mbedtls_ssl_get_session`.
+     This API has deep copy of the session, and the peer
+     certificate is not lost. #926
 
 Changes
    * Change the shebang line in Perl scripts to look up perl in the PATH.