Add style coding guidelines (#408)
Add style coding guidelines (#408)

* (GH-407) Add code style and standards

* (GH-407) Update TOC and headings

* (GH-407) Fixing markdown errors

* (GH-407) Removed prerequisites link

* (GH-407) Add link to unofficial Posh style guide

* (GH-407) Add VS Code recommendation for PS code

mwrock/boxstarter,mwrock/boxstarter