Add style guide link for `Style/TopLevelMethodDefinition`
Add style guide link for `Style/TopLevelMethodDefinition`

Follow https://github.com/rubocop/ruby-style-guide/pull/872

rrosenblum/rubocop,bbatsov/rubocop,maxjacobson/rubocop,bbatsov/rubocop,maxjacobson/rubocop,tejasbubane/rubocop,maxjacobson/rubocop,rrosenblum/rubocop,rrosenblum/rubocop,tejasbubane/rubocop,tejasbubane/rubocop