add more orientation to github web interface

[evanwill]

not exactly sure where, but there seems to be a gap for CB-GH users--we do step by step to setup git, clone, and start editing on local machine, but don't actually ever do a step by step about how to edit files on github web interface. There is step by step for CB-GH uploading metadata and objects, but not how to start editing the _config or anything else.

[evanwill]

also need to add a note about markdown previews on github, i.e. github preview doesn't relate to what will work on the built out site, because github preview doesn't have Liquid and rewrites links relative to the repository (which doesn't relate to how the website is going to be).
So things that work on the website, aren't going to show up correctly on github markdown preview, and a few things that work on github preview, aren't going to work on the website.

[evanwill]

the software > GitHub page mentions . vs code, but maybe mention more in this orientation content.

maybe in "Software", add section talking about software for CB-GH--> explain how you can do everything in github web interface, provide intro to features, web editor, and vs code web editor?