Prevent attribute missing warnings

[HeroProtagonist]

Fixes rubocop/rubocop#9150

These warnings appear because antora enables them by default. asciidoctor/asciidoctor#3482 (comment)

When the value is set to skip which assciidoctor has as default (as mentioned here https://discuss.asciidoctor.org/skipping-reference-to-missing-attribute-tp7687p7691.html) the warnings are not shown.

[bbatsov]

Hmm, won't this suppress the real problems as well, though? I think I already fixed the cause of the warnings at some point in the past, but they are still in the build output because we keep building the old versions of the docs as well (where the problem is not fixed).

Seems the only good solution would be to drop the old versions from the build, so they don't generate a lot of noise, but that might break some linking. Tough situation. //cc @rubocop/rubocop-core

[koic]

Seems the only good solution would be to drop the old versions from the build, so they don't generate a lot of noise, but that might break some linking.

I think it's possible to drop old versions of the build, leaving a few generations. The reason is as follows.

• Since RuboCop 1.0, there will be no major changes to the doc for compatibility.
• Old resources are not completely lost. (e.g. https://docs.rubocop.org/rubocop/0.93/index.html)

I'm not sure how many generations to leave. 3 to 5 generations may be enough. But I'm not confident.

Anyway, I don't have a strong opinion, so I'm interested in other opinions as well 😃

[koic]

Hmm, won't this suppress the real problems as well, though?

I'm going to close this proposal because I agree with this opinion. Thank you.