Add "blog-template" (can be other name) to our `/examples` folder

[olayway]

Acceptance

• [ ] new example project in /examples folder, named e.g. blog-template
  • [ ] has /content/blog folder with a few example blog posts
  • [ ] has a getter in /content/getters (for now let's put it here as for all the other projects, but see my comment here https://github.com/flowershow/flowershow/issues/325#issuecomment-1427934734)
  • [ ] has basic config in content/config.js
  • [ ] has /content/blog/index.md page with a list of all blog posts (using our BlogsList component)
  • [ ] has comments enabled for blog pages (with info in README about required env variables)
  • [ ] has README file with some info about what this template includes
  • ...
• [ ] update our tutorial (#396) accordingly
• ...

[olayway]

@rufuspollock what do you think?