Update comments of mbedtls_platform_random_delay
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index d6ee886..96c96a3 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -241,15 +241,21 @@
/**
* \brief Random delay function.
*
- * Function implements random delay by incrementing local variable
- * randomized number of times.
+ * Function implements a random delay by incrementing a local
+ * variable randomized number of times (busy-looping).
+ *
+ * Duration of the delay is random as number of variable increments
+ * is randomized.
*
* \note Currently the function is dependent of hardware providing an
* rng with MBEDTLS_ENTROPY_HARDWARE_ALT.
*
- * \param num Max-value for the local variable increments.
+ * \param num Max-value for the number of local variable increments, must be
+ * less than INT_MAX. Total number of variable increment will be
+ * randomized between 1 and num.
*
- * \return In success number of increments, -1 in case of errors.
+ * \return In success number of increments made.
+ * \return Negative value in case of errors.
*/
int mbedtls_platform_random_delay( size_t num );