[PATCH 2/2] Document the string_list structure

@@ -8,6 +8,12 @@ struct string_list_item {
 
 typedef int (*compare_strings_fn)(const char *, const char *);
 
+/* A resizable array of strings. The strings are owned if
+ * 'strdup_strings' is set. It can be used as a sorted array, and a
+ * custom comparison may be given in 'cmp'. The field 'items[i].util'
+ * may be used to implement an array of pairs. In that case, the
+ * caller is responsible for managing memory pointed to by 'util'.
+ */
 struct string_list {
 	struct string_list_item *items;
 	unsigned int nr, alloc;