Function resolve_document 

pub fn resolve_document(
    resolver: &Resolver<'_>,
    nitpick: &NitpickConfig<'_>,
    docname: &str,
    doctree: &mut Doctree,
    path: &Path,
) -> DocumentResolution

Resolve every pending_xref in one document, rewriting the tree the way ReferencesResolver.run does: the node is replaced by the reference that resolution built, or by its own content node when it failed.