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

Matthias Bussonnier <bussonniermatthias@gmail.com> added the comment: See the `compile()` documentation for the difference between eval/single/exec: https://docs.python.org/3/library/functions.html#compile `exec` is meant for multiline program, for example you would "exec" the string read from a file to get a module. I don't think we should re-document what each of these does, but list the possible values that compile_command/CommandCompiler() can take. ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue38872> _______________________________________