Add CI Docs (Part II)

[XAML-Knight]

Fixes #2

Closes loose end on #42 upon @RosarioPulella's departure

• Security on @RosarioPulella's GitHub repo prevent adding new changes on to the original PR Add CI Docs #42

What changes does this PR introduce?

Add some overview style docs about our CI pipeline and its various components.

PR Checklist

Please check if your PR fulfills the following requirements:

• Opened a relevant issue and provided the reference # above
• Correctly picked the forked new branch to base the change off (main)
• Ran against a spell and grammar checker

Other information

[michael-hawker]

@azchohfi mind taking a minute to do a pass too? I know we can add more detail over time but should be good to get us started.

@XAML-Knight Thanks, but also don't forget to add a link in the TOC file (sidebar: https://github.com/CommunityToolkit/WindowsCommunityToolkit-wiki/blob/main/_sidebar.md) Not sure if makes sense under Project Structure or just Development/Testing?