Pass --extern-html-root-takes-precedence

Author: jyn514

src/docbuilder/rustwide_builder.rs

@@ -616,6 +616,7 @@ impl RustwideBuilder {
                 r#"--config=doc.extern-map.registries.crates-io="https://docs.rs/{{pkg_name}}/{{version}}/{}""#,
                 target
             ),
+            "--extern-html-root-takes-precedence".into(),
         ];
         if let Some(cpu_limit) = self.config.build_cpu_limit {
             cargo_args.push(format!("-j{}", cpu_limit));