Fix typo in mbedtls_ssl_set_bio description.

Description referred to mbedtls_ssl_sent_t callback,
but the callback is named mbedtls_ssl_send_t.

Signed-off-by: Christopher Moynihan <christophm@gmail.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index d3ee3c4..fe33ac8 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1409,7 +1409,7 @@
  * \note           For DTLS, you need to provide either a non-NULL
  *                 f_recv_timeout callback, or a f_recv that doesn't block.
  *
- * \note           See the documentations of \c mbedtls_ssl_sent_t,
+ * \note           See the documentations of \c mbedtls_ssl_send_t,
  *                 \c mbedtls_ssl_recv_t and \c mbedtls_ssl_recv_timeout_t for
  *                 the conventions those callbacks must follow.
  *