[Feature] Document Delay functionality

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Description

Since most of tokio isn't supported (since it does not compile to wasm) I'm not certain if there's a real pattern to support a Cloudflare worker, written in Rust using the workers-rs package, to forward a request to another server using reqwest, with an incremental backoff in the case of a 429 rate limit. It would be the goal of this feature to support in the worker runtime some method of sleeping the worker thread for some incremented period of time until either the request finally succeeds, or Cloudflare kills the thread for taking too long as I believe is already expected behavior with workers.