Add an example site

[stephlocke]

We need to have a decent way to test things out and to enable us to potentially submit to the themes directory one day.

Test your theme against https://github.com/gohugoio/hugoBasicExample
If your theme doesn’t fit into the Hugo Basic Example site, we encourage theme authors to supply a self-contained Hugo site in /exampleSite.

https://gohugo.io/contribute/themes/

[maelle]

I'd even vote for two example sites: more work maintaining, but to be able to show you can really add the theme to any other theme. The two sites would look different but both benefit from this utility belt. Does this make any sense?