a built-in preprocessor (enabled by default) which will transform all README.md chapters to index.md so foo/README.md can be accessed via the url foo/ when published to a browser
If only foo/README.md exists, then linkcheck incorrectly flags links to foo/ because foo/index.md doesn't exist. This is a false positive because the link won't actually be broken.
The index preprocessor is
If only
foo/README.mdexists, then linkcheck incorrectly flags links tofoo/becausefoo/index.mddoesn't exist. This is a false positive because the link won't actually be broken.