Ruby

hash.c: improve docs for Hash#{size,length}

• hash.c: [DOC] shorten example code for Hash#{size,length}
  and mention aliases at the end; also enable links.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65036 b2dd03c8-39d4-4d8f-98ff-823fe69b080e