minor mods in documentation

check trello for features/comments

include/dmmlib/heap.h

@@ -49,7 +49,10 @@
 typedef uint8_t knob_state_t;
 #endif /* WITH_KNOBS */
 
-/** A structure to represent a maptable node. */
+/** A structure to represent a maptable node.
+ *  This is a single-linked list holoding blocks of specific size, thus acting
+ *  as a fixed list within the allocator.
+ */
 typedef struct maptable_node_s {
 	unsigned int size; /**< The size of the blocks of the fixed list. */
 	void *fixed_list_head; /**< Pointer to the head node of the fixed list. */