[docs] [issue38872] Document exec symbol for codeop.compile_command

Change by miss-islington <mariatta.wijaya+miss-islington@gmail.com>: ---------- nosy: +miss-islington nosy_count: 5.0 -> 6.0 pull_requests: +19403 pull_request: https://github.com/python/cpython/pull/20098 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue38872> _______________________________________