hash.c: exception examples

* hash.c (rb_hash_dig): [DOC] add examples of exceptions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53667 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

hash.c

@@ -2702,6 +2702,8 @@ rb_hash_any_p(VALUE hash)
  *
  *   g = { foo: [10, 11, 12] }
  *   g.dig(:foo, 1)                    #=> 11
+ *   g.dig(:foo, 1, 0)                 #=> TypeError: Fixnum does not have #dig method
+ *   g.dig(:foo, :bar)                 #=> TypeError: no implicit conversion of Symbol into Integer
  */
 
 VALUE