[docs] [issue37134] Use PEP570 syntax in the documentation

Change by Pablo Galindo Salgado <pablogsal@gmail.com>: ---------- pull_requests: +13752 pull_request: https://github.com/python/cpython/pull/13874 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue37134> _______________________________________