Write a document to introduce RBS Rails and Steep to a real Rails application

[pocke]

Write a document to introduce RBS Rails and Steep to a real Rails application

[Uaitt]

Hey @pocke.
In the past months I have been studying and discovering the world of RBS and all of its tools. Your gem is definitely useful and works well for generating RBS for models/helpers in a rails app, however I think that it's lack of a "getting started" guide for adding RBS support on a rails application is slowing down adoption a bit. There is no article online about this topic (I was able to find guides for adding RBS on pure-ruby projects, not for rails ones), and it's really hard to find informations.

I am here to propose myself to write something like a GETTING_STARTED.md, that introduces newbies to how to add RBS support for a rails application from scratch (using a combination of rbs collection - steep and rbs_rails, and of course custom signatures) . I can also update your current README.md a little bit, perhaps if you can link me the known issue that you mention in the current issue description.

Keep in mind that I have already watched your talk at RubyKaigi this year.

Do you mind if I try, and open a PR that links to this issue? You will be of course free to reject it or to give me any tips in order to let me improve the guide. Let me know if I can start, please :)