Small typo in programmer's documentation.

 * zeroes and creates a memory block resource representing this memory

 * chunk in the pool @p.

 *

 * Please note that mb_alloc() returns a pointer to the memory

 * Please note that mb_allocz() returns a pointer to the memory

 * chunk, not to the resource, hence you have to free it using

 * mb_free(), not rfree().

 */