hash.c: [DOC] fix book title in example

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57753 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

hash.c

@@ -4363,7 +4363,7 @@ env_update(VALUE env, VALUE hash)
  *  Hashes are an easy way to represent data structures, such as
  *
  *    books         = {}
- *    books[:matz]  = "The Ruby Language"
+ *    books[:matz]  = "The Ruby Programming Language"
  *    books[:black] = "The Well-Grounded Rubyist"
  *
  *  Hashes are also commonly used as a way to have named parameters in