Proof read the S4 Mk3 documentation

[acolombier]

In order to improve the quality of the documentation for first class Mixxx device, the S4 Mk3 documentation should be refined to ensure a premium support

[acolombier]

@ywwg just for tracking

[ywwg]

is the request to just read over the existing doc and tidy it up?

[acolombier]

That would be great yes. I'm sure there is a few things that could use some better English wording. Also, it isn't impossible that some information is missing or incorrect

[ywwg]

I have started working on this, I'll post a PR when I get through it