Style/Documentation macro-only check is incorrect

[ghiculescu]

This does not get a lint error:

class Thing < ApplicationRecord
  belongs_to :user
end

I think it should, because it is a class with legitimate contents, but no documentation.

I think the changes made in #8812 have introduced a false positive.

---

Expected behavior

Style/Documentation lint error, as the class has no documentation.

Actual behavior

No lint error.

RuboCop version

1.40.0 (using Parser 3.1.3.0, rubocop-ast 1.24.0, running on ruby 3.1.3) [x86_64-darwin20]
  - rubocop-minitest 0.25.0
  - rubocop-performance 1.15.1
  - rubocop-rails 2.17.3
  - rubocop-thread_safety 0.4.4