Can `./x doc xxx` be exercised in PR CI or earlier?

[jieyouxu]

Tool docs like ./x doc src/tools/compiletest seemingly are run very late into the full CI pipeline, but that seems relatively easy and cheap to either run in PR CI or perhaps earlier in full CI? That might help to catch trivial broken intradoc links which can fail full CI like 2 hours in...

Not sure about compiler/std docs, but some tool docs might be okay to move earlier into the pipelines?

T-infra zulip link: https://rust-lang.zulipchat.com/#narrow/channel/242791-t-infra/topic/Can.20some.20doc.20checks.20happen.20in.20PR.20CI.20or.20happen.20earlier.3F

[jieyouxu]

Didn't quite figure out when the link check can be too late.