Clear instruction on installing OpenSCAD

[venablesshooting]

Prerequisites

• I have read the documentation and the proposed feature is not implemented.

Description

As someone who has just come across kikit I tried to use the stencil function for the better part of an hour. I struggled with exactly what stencil command requires only to have issues with openscad not being in path. For the unitiated this is deeply confusing and lead me to a large amount of research to finally fix the issue of openscad not being in path. It would massively help new users to have documentation detailing this so they don't have to struggle like I did. If needed I am happy to create said documentation for windows

[yaqwsx]

Feel free to open a PR for such a documentation improvement (I always thought that Google gives a nice step-by-step tutorial: https://www.google.com/search?q=how+to+add+program+to+path+windows)