Document common cargo commands

[Darksonn]

Currently you have to look inside the ci directory to find the commands, which does not lend itself very well to discoverability for new users. I personally found it difficult to find some of these, and I'm not the only one.

You can view the rendered markdown here.

[dekellum]

Should there also be a suggestion for running loom?

[Darksonn]

Sure, what is the command?

[dekellum]

That's the the thing, I can never remember it! (I'll try and dig it up...)

[dekellum]

As my timing wasn't great, this could always be added as a followup if it is at all questionable! Draft verbiage, change as desired:

Also run the loom tests the way they are run in CI:

cd tokio # tokio crate in workspace
LOOM_MAX_PREEMPTIONS=1 RUSTFLAGS="--cfg loom" \
    cargo test --lib --release --features full -- --test-threads=1 --nocapture

Note this will first compile a release build, but in combination with LOOM_MAX_PREEMPTIONS=1 allows the loom tests to complete in a reasonable amount of time.

[Darksonn]

Can we merge this?

[LucioFranco]

@Darksonn you got three approvals :) feel free to merge!