Merge pull request #2876 from TheBlueMatt/2024-02-2863-doc-nits

[rust-lightning] / bench / README.md

This crate uses criterion to benchmark various LDK functions.

It can be run as `RUSTFLAGS=--cfg=ldk_bench cargo bench`.

For routing or other HashMap-bottlenecked functions, the `hashbrown` feature
should also be benchmarked.