vm_method.c: [DOC] example of respond_to_missing?

* vm_method.c (obj_respond_to_missing): [DOC] respond_to_missing? is
  used in the example of BasicObject.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42736 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

vm_method.c

@@ -1639,7 +1639,7 @@ obj_respond_to(int argc, VALUE *argv, VALUE obj)
  *  When the method name parameter is given as a string, the string is
  *  converted to a symbol.
  *
- *  See #respond_to?.
+ *  See #respond_to?, and the example of BasicObject.
  */
 static VALUE
 obj_respond_to_missing(VALUE obj, VALUE mid, VALUE priv)