Fix, improve and add comments

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index d649266..f8c5948 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1615,11 +1615,11 @@
      *  ClientHello writing preparation stage with the previously negotiated
      *  TLS version.
      *
-     *  On client side, updated to the TLS version selected by the server for
-     *  the handshake when the ServerHello is received.
+     *  On client side, it is updated to the TLS version selected by the server
+     *  for the handshake when the ServerHello is received.
      *
-     *  On server side, updated to the TLS version the server selects for the
-     *  handshake when the ClientHello is received.
+     *  On server side, it is updated to the TLS version the server selects for
+     *  the handshake when the ClientHello is received.
      */
     mbedtls_ssl_protocol_version MBEDTLS_PRIVATE(tls_version);