merge revision(s) 40374: [Backport #8292]

	* README.EXT.ja (Data_Wrap_Struct): Remove a description about
	  orphan argument. Oh, I renamed the argument name without
	  changing description at r36180... Sorry....
	  Patch by Makoto Kishimoto. Thanks!!! [ruby-dev:47269] [Bug #8292]

	* README.EXT.ja (Data_Make_Struct): Add a sample code that describes
	  how it works.
	  Patch by Makoto Kishimoto. Thanks!!! [ruby-dev:47269] [Bug #8292]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@40378 b2dd03c8-39d4-4d8f-98ff-823fe69b080e