Add Mac OS tracy info to profiling docs

[mweatherley]

Explanation

I got kind of lost on this earlier (the Tracy docs are not very helpful) and required some assistance, so I thought it might be helpful to add this somewhere in the profiling docs. The way it's presently inserted is kind of awkward, but I don't know enough about the other operating systems to make similar sections for them, which I think would be helpful, since it's going to be different on each one.