`timedOut` instead of `timedout`?

`timedout` is hard to read and looks out of place next to [`headersSent`](https://expressjs.com/en/api.html#res.headersSent), [`statusCode`](https://nodejs.org/api/http.html#responsestatuscode), [`lastModified`](https://expressjs.com/en/api.html) etc.

Would it make sense to rename it, or at least add an option to rename it? I could implement and test it and make a PR.