def man_dir(path = nil)
      if @man_dir.nil? || path
        man_path = path || File.expand_path('../man', __FILE__)

        if File.directory?(man_path)
          @man_dir = man_path
        else
          fail "Manuals directory `#{man_path}` does not exist"
        end
      end
      @man_dir
    end
def man_dir(path = nil)
      if @man_dir.nil? || path
        man_path = path || File.expand_path('../man', __FILE__)

        if File.directory?(man_path)
          @man_dir = man_path
        else
          fail "Manuals directory `#{man_path}` does not exist"
        end
      end
      @man_dir
    end
Full path to manual directory

 @return [String]

 @api private