[boly38]

add sample with promise to discuss about #35

[jhurliman]

Thanks @boly38 for the Promise example and investigation of #35. The library now has a native Promise API and options-object constructor; the callback wrapper and positional constructor in this old sample no longer apply. #105 includes runnable await-based pacing examples and a deterministic regression for the reported 5,000-request scenario. Closing this obsolete example PR with credit here; the non-atomic multi-limiter composition caveat remains documented in #35.