docs: highlight features (#59)

README.md

@@ -24,3 +24,9 @@ Set `make_anchor=True` when calling `gendoc` function and use standard ref synta
 The id is the same as the argument path. Variant types would be in square brackets.
 
 Please refer to test files for detailed usage.
+
+## Additional features
+
+- [PEP 484](https://peps.python.org/pep-0484/) type annotations
+- Native integration with [Sphinx](https://github.com/sphinx-doc/sphinx), [DP-GUI](https://github.com/deepmodeling/dpgui), and [Jupyter Notebook](https://jupyter.org/)
+- JSON encoder for `Argument` and `Variant` classes