https://www.freecodecamp.org/news/build-a-developer-blog-from-scratch-with-gatsby-and-mdx/
- Put a space between the key and value: categories:[bla] does not work categories: [bla] works
netlify-labs/netlify-plugin-a11y#3 Test netlify builds locally, to catch errors locally
- ONCE: npm install @netlify/build -g
- cd src && netlify-build