State that all error codes are negative
* \brief Function return status.
*
* This is either #PSA_SUCCESS (which is zero), indicating success,
- * or a nonzero value indicating that an error occurred. Errors are
+ * or a small negative value indicating that an error occurred. Errors are
* encoded as one of the \c PSA_ERROR_xxx values defined here. */
/* If #PSA_SUCCESS is already defined, it means that #psa_status_t
* is also defined in an external header, so prevent its multiple
