libopae: clarify fpgaEnumerate() doxygen
Update the doxygen for parameters 'filters' and 'num_filters'
to reflect the two ways of achieving a "match-all" query.
@@ -71,9 +71,12 @@ extern "C" {
* @param[in] filters Array of `fpga_properties` objects describing the
* properties of the objects that should be returned. A
* resource is considered matching if its properties
- * match any one of the supplied filters. Passing NULL
- * will match all FPGA resources present in the system.
- * @param[in] num_filters Number of entries in the `filters` array.
+ * match any one of the supplied filters. To match all
+ * FPGA resources, pass an empty filters object (one
+ * without any filter criteria set) or pass a NULL
+ * filters parameter with num_filters set to 0.
+ * @param[in] num_filters Number of entries in the `filters` array, or 0 to
+ * match all FPGA resources when `filters` is NULL.
* @param[out] tokens Pointer to an array of fpga_token variables to be
* populated. If NULL is supplied, fpgaEnumerate() will
* not create any tokens, but it will return the
