chore: Example style guide

[moonmeister]

Create a "style guide" for Examples. The goal of this should be to help keep examples on target and any complication should be around the problem at hand. e.g.

• Minimal external dependencies, prefer none/web platform packages over 3rd party dependencies
• Pure CSS
• No UI libraries
• No Typescript
• Related examples should have similar things (e.g. fetch and Apollo fetching examples should be the same site with only the client changed)
• Lots of comments explaining what and why
• etc...

Tasks

• create the written "style guide" for examples
• research and propose a shared styling system that can be reused across examples (e.g. a stylesheet that can be copied and pasted)