cJSON_Add..ToObject: Add comment to header file

cJSON.h

@@ -245,7 +245,8 @@ CJSON_PUBLIC(cJSON_bool) cJSON_Compare(const cJSON * const a, const cJSON * cons
 
 CJSON_PUBLIC(void) cJSON_Minify(char *json);
 
-/* Macros for creating things quickly. */
+/* Helper functions for creating and adding items to an object at the same time.
+ * They return the added item or NULL on failure. */
 CJSON_PUBLIC(cJSON*) cJSON_AddNullToObject(cJSON * const object, const char * const name);
 CJSON_PUBLIC(cJSON*) cJSON_AddTrueToObject(cJSON * const object, const char * const name);
 CJSON_PUBLIC(cJSON*) cJSON_AddFalseToObject(cJSON * const object, const char * const name);