Fixed documentation Python script handling of null

The script would serialize null values as "None" in the Markdown files it produces, which is not great. It's better to leave empty strings.

packaging/format-docs.py

@@ -83,7 +83,7 @@ def format_docs(version, collectionName, types):
 
                         print(f'| {prop["PropertyName"]} | {defaultValue} | {prop["UserFriendlyType"]} | {prop["Description"]} |')
                     else:
-                        print(f'| {prop["PropertyName"]} | {prop["DefaultValue"]} | {prop["UserFriendlyType"]} | {prop["Description"]} |')
+                        print(f'| {prop["PropertyName"]} | {prop["DefaultValue"] or ""} | {prop["UserFriendlyType"]} | {prop["Description"]} |')
 
 if __name__ == "__main__":
     input_stream = io.TextIOWrapper(sys.stdin.buffer, encoding='utf-8-sig')