rational.c: fix rdoc

	* rational.c: [DOC] fix wrong indentations and comment out some lines
	  in code examples to make them valid Ruby code and syntax highlighted
	  on the rendered page.

	[ci skip] [Bug #13233]
	Author: Marcus Stollsteimer sto.mar@web.de



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@62126 b2dd03c8-39d4-4d8f-98ff-823fe69b080e