refine description of pic_get_args

vm.c

@@ -35,26 +35,26 @@ pic_get_proc(pic_state *pic)
 }
 
 /**
- * char type
- * ---- ----
- *  o   object
- *  i   int
- *  I   int with exactness
- *  f   float
- *  F   float with exactness
- *  s   string object
- *  z   c string
- *  m   symbol
- *  v   vector object
- *  b   bytevector object
- *  c   char
- *  l   lambda object
- *  p   port object
- *  d   dictionary object
- *  e   error object
+ * char type                 desc.
+ * ---- ----                 ----
+ *  o   pic_value *          object
+ *  i   int *                int
+ *  I   int *, bool *        int with exactness
+ *  f   double *             float
+ *  F   double *, bool *     float with exactness
+ *  s   pic_str **           string object
+ *  z   char **              c string
+ *  m   pic_sym *            symbol
+ *  v   pic_vec **           vector object
+ *  b   pic_blob **          bytevector object
+ *  c   char *               char
+ *  l   struct pic_proc **   lambda object
+ *  p   struct pic_port **   port object
+ *  d   struct pic_dict **   dictionary object
+ *  e   struct pic_error **  error object
  *
  *  |                        optional operator
- *  *  variable length operator
+ *  *   int *, pic_value **  variable length operator
  */
 
 int