Add rich result data to blog articles

[mschoettle]

Via: astral-sh/uv#11164 (https://github.com/FishAlchemist/uv/blob/main/docs/.overrides/main.html)

See: https://developers.google.com/search/docs/appearance/structured-data/article

Test tool: https://search.google.com/test/rich-results?hl=en

[mschoettle]

Maybe the social plugin would be good: https://squidfunk.github.io/mkdocs-material/plugins/social/

[mschoettle]

As a follow-up to #172 it would be good to add short descriptions to the most important blog posts. Basically, explaining what the post is about. That way, the social cards will show that descriptions from the metadata instead of the site description.