header: explain PrintPreallocated return value

cJSON.h

@@ -83,7 +83,7 @@ extern char  *cJSON_Print(const cJSON *item);
 extern char  *cJSON_PrintUnformatted(const cJSON *item);
 /* Render a cJSON entity to text using a buffered strategy. prebuffer is a guess at the final size. guessing well reduces reallocation. fmt=0 gives unformatted, =1 gives formatted */
 extern char *cJSON_PrintBuffered(const cJSON *item, int prebuffer, int fmt);
-/* Render a cJSON entity to text using a buffer already allocated in memory with length buf_len */
+/* Render a cJSON entity to text using a buffer already allocated in memory with length buf_len. Returns 1 on success and 0 on failure. */
 extern int cJSON_PrintPreallocated(cJSON *item, char *buf, const int len, const int fmt);
 /* Delete a cJSON entity and all subentities. */
 extern void   cJSON_Delete(cJSON *c);