[fix GH-872][ci skip]
* doc/syntax/methods.rdoc: ditto.
* ext/digest/sha2/sha2.c: ditto.
* ext/socket/ipsocket.c: ditto.
* ext/tk/*: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50320 b2dd03c8-39d4-4d8f-98ff-823fe69b080e