Improve "How does it work" section in README.md

[danielhoherd]

In the "How does it work" section of the README.md, the text states "It simply scans /proc for interesting commands", however this tool runs on macOS, which does not have the /proc filesystem. It would be nice to know a bit more about how this works outside of linux.

[BestPig]

You can check my initial commit for mac compatibility (36f3aa8).
Initially progress was only on Linux it's why its describe like that, but some support to osx was added.

The concept is still the same, but it doesn't list /proc but use some macOS alternative by calling function proc_listpids and proc_name and then getting more on processes via proc_pidinfo and proc_pidfdinfo