Fixing some typos in the documentation

Hiya,

I'm new and am going through the documentation for the first time. I have noticed some typos so figured I'll fix them while I'm here.

As per  linuxcnc.org/docs/stable/html/code/contr...rview_of_the_process , this is my attempt to communicate with the project developers and let you all know what I am hacking on, explain what I am doing and why.

I've cloned the repo and will submit a pull request with some changes as soon as I figure out how to do that.

I'll also send a message to the mailing list. Please let me know if anyone has any objections or concerns.

Regards,
John

The only concern I have is why my hip has been so sore this week.
On a serious note it's great to see someone getting involved and fixing the stuff that can fall through the cracks.