Prose end-to-end testing with recipes

[peterbe]

We've had at least two errors now where the prose sections are busted. https://github.com/mdn/stumptown-experiment/issues/32 and https://github.com/mdn/stumptown-experiment/issues/37

There's not really anything obviously wrong with the Markdown in those files. Maybe there might be, but that's the point.

What I would like to have is something that reads the recipes, understands which sections are mandatory and then validates the built JSON files for each of these.

Let's keep it simple and make an end-to-end test exclusively for this. It'd need to first run the npm run build-json ... and then iterate over the produced .json files and do checks including loading in the recipe.