Readme samples use incorrectly 1X and 2X as size arguments, but that doesn't work

[timolehto]

Gives error:

[8] pry(main)> heroku.formation.update s.name, 'web', { quantity: 1, size: "1X" }
Excon::Error::UnprocessableEntity: Expected([200, 201, 202, 204, 206, 304]) <=> Actual(422 Unprocessable Entity)
from /Users/timo/.rvm/gems/ruby-2.3.0@api/gems/excon-0.60.0/lib/excon/middlewares/expects.rb:7:in `response_call'

As one might expect, this works:

heroku.formation.update s.name, 'web', { quantity: 1, size: "Standard-1X" }