Update elm/pdf.py

Co-authored-by: Paul Pinchuk <[email protected]>

elm/pdf.py

@@ -345,7 +345,7 @@ def convert_to_txt(self, txt_fp=None, separator='    ',
         ----------
         txt_fp: str, optional
             Optional Directory for output txt file.
-        separator : str
+        separator : str, optional
             Heuristic split string to look for spaces between columns
         clean_header_kwargs : dict, optional
             Optional kwargs to override clean_headers kwargs