fixing a typo in comment
@@ -1015,7 +1015,8 @@ int MBEDTLS_DEPRECATED mbedtls_x509write_crt_set_serial(
* \param ctx CRT context to use
* \param serial A raw array of bytes containing the serial number in big
* endian format
- * \param serial_len Length of the previous input buffer buffer
+ * \param serial_len Length of valid bytes (expressed in bytes) in \p serial
+ * input buffer
*
* \return 0 if successful, or
* MBEDTLS_ERR_X509_BAD_INPUT_DATA if the provided input buffer
