README updates?

[djc]

Following up on https://phanpy.social/#/hachyderm.io/s/112571606961741408, the root README.md has:

samply works on macOS and Linux. Windows support is planned.

But the samply crate README.md has:

At the moment, the macOS implementation works best. The Linux implementation is extremely new and experimental. There is no Windows implementation yet.

Per the Mastodon response from @jrmuizel, both of these might not be up to date? I would suggest maybe merging the README's so you don't forget to make updates to both? (The crate-level one gets shown on crates.io.)

Might also want to keep https://nnethercote.github.io/perf-book/profiling.html up to date.

I think samply is great, have been it using this week on rustup, thanks for building it! (It is dampening my motivation for maintaining cargo-flamegraph, so will try to make sure to point it out to people.)