Fix doc.

[akimd]

The current documentation reads:

      # Note that `kwargs` node is just a replacement for `hash` argument,
      # so if there's are multiple arguments (or a `kwsplat`) all of them
      # are wrapped into `kwargs` instead of `hash`:
      #
      # ```
      # (send nil :foo
      #   (hash
      #     (pair
      #       (sym :a)
      #       (int 42))
      #     (kwsplat
      #       (send nil :b))
      #     (pair
      #       (sym :c)
      #       (int 10))))
      # ```

I believe the last hash was meant to be kwargs.

[iliabylich]

Thank you!