Backport a doxygen note from development for `mbedtls_ssl_conf_max_frag_len()`
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 9f44413..da0c5ca 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -2115,6 +2115,10 @@
  *                 negotiate with the server during handshake)
  *                 (Default: #MBEDTLS_SSL_MAX_FRAG_LEN_NONE)
  *
+ * \note           With TLS, this currently only affects ApplicationData (sent
+ *                 with \c mbedtls_ssl_read()), not handshake messages.
+ *                 With DTLS, this affects both ApplicationData and handshake.
+ *
  * \note           On the client side, the maximum fragment length extension
  *                 *will not* be used, unless the maximum fragment length has
  *                 been set via this function to a value different than