Update src/readme.rs

Author: rafaelbeckel

src/readme.rs

@@ -14,7 +14,7 @@ pub fn copy_from_crate(crate_data: &CrateData, path: &Path, out_dir: &Path) -> R
         "crate directory should exist"
     );
     assert!(
-        fs::metadata(out_dir).ok().map_or(false, |m| m.is_dir()),
+        fs::metadata(&out_dir).ok().map_or(false, |m| m.is_dir()),
         "crate's pkg directory should exist"
     );