Better document type options

Author: mwcraig

astrowidgets/interface_definition.py

@@ -96,7 +96,7 @@ def save(self, filename: str | os.PathLike, overwrite: bool = False) -> None:
 
         Parameters
         ----------
-        filename : str
+        filename : str or `os.PathLike`
             The file to save to. The format is determined by the
             extension.