closure_tree:config generator missing

[paddy-hack]

I was going through the steps in the README.md file's Installation section and saw the NOTE to generate an initializer. Trying that out I got

$ bin/rails g closure_tree:config
Could not find generator 'closure_tree:config'. (Rails::Command::CorrectableNameError)
Did you mean?  closure_tree:migration
Run `bin/rails generate --help` for more options.

It looks like the README.md was not updated to follow the changes in #457.