Update ssl_tls.c
Clarification in comments
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 0e7bd4d..2abd18b 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3396,7 +3396,8 @@
* - if anything goes wrong, return a specific error code
*
* mbedtls_ssl_read_record() will ignore the record if anything else than
- * MBEDTLS_ERR_SSL_CLIENT_RECONNECT or 0 is returned.
+ * MBEDTLS_ERR_SSL_CLIENT_RECONNECT or 0 is returned, although this function
+ * cannot not return 0.
*/
static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
{
