2457: Clarify installation instructions r=matklad a=fintelia
In particular it is necessary to clone the repository before running the other commands. I also removed the `cargo install` side note because it didn't actually work (running the command just produces an error that --package isn't a recognized flag) and added a tldr code block with the list of commands to run.
Co-authored-by: Jonathan Behrens <fintelia@gmail.com>