check-doc-refs.sh's relative arm resolved every link against the linking
file's directory. That is right for markdown and wrong for a .rs doc
comment: rustdoc emits the href verbatim onto a page under
target/doc/<crate>/<module...>/, so the link resolves against THAT
directory instead.
The consequence was a false pass, not a miss -- a link resolving from the
source dir got certified while rendering broken in the published docs.
Reproduced against main's script: a `](../../docs/README.md)` planted in
hive-forge/src/client.rs resolves from hive-forge/src/ and the old rule
exits 0.
Refused rather than resolved rustdoc-aware. The repo has zero relative
links in .rs doc comments (measured on 54daf9ac), so nothing needs the
second reader, and the backticked repo-root form the root arm already
gates renders correctly under both. Inferring module nesting would be
machinery in service of a form nothing uses.
Closes#3928
8f56f86df5