### Description Add rst2rfcxml(https://github.com/dthaler/rst2rfcxml/) to Author Tools. Files with extension `.rst` will be converted to `xml` using `rst2rfcxml`. ### Code of Conduct - [X] I agree to follow the [IETF's Code of Conduct](https://github.com/ietf-tools/.github/blob/main/CODE_OF_CONDUCT.md)