Declare a Rails version policy

[andyw8]

There are several places in the guide that refer to older versions of Rails that are no longer supported.

Removing these would help to reduce noise and improve readability.

A notice could be added to indicate that the guide only covers supported Rails versions.

[pirj]

I like this, less noise, less maintenance.
On the other hand, I’ve seen too often in practice that even big companies run older, unsupported Rails versions.

The same applies to Ruby versions. Do we have some similar agreement in the Ruby style guide?

Technically, we could git tag guides, and if someone is on an earlier Ruby/Rails/RSpec/Capybara/… version, they could refer to the older guide version on GitHub.
This is similar to Rails guides, they go as early as 2.3

Publishing of older versions on rubystyle.guide feels optional.

[pirj]

#361 (comment)