Fixed powershell commands for Windows Runner

What does this MR do?

The commands I am fixing were confusing and would simply not work if they were ran as they were (they didn't work for me). I have replaced them with the powershell commands that will actually work and the docs are no longer making any leaps of faith and assumptions about the end customer who is following the docs.

I have also made clearer the context in which these operations are performed, more explicitly I've also added commands and instructions to be clearer on the path where everything is run and when.