Wrong parameter in rustdoc of Delay's reset method

The Delay reset method takes a `dur: Duration` parameter but the docs say "Resets this timeout to an new timeout which will fire at the time specified by `at`".

The docs mention the wrong parameter and the semantics seem misaligned.

Minor tweak: "**an** new timeout" should be "**a** new timeout".

Locate the Delay::reset entry point and read its rustdoc alongside the method signature. Update the documentation to refer to the dur parameter, correct the timeout wording and article, then run rustdoc or the project's documentation checks to confirm the rendered text.

Written by the indexing model from the issue text.