WDYT of switching to commonmark-0.30-example-xxx.md for file names? If we stick with example-xxx.md, git will detect files as modified instead of renamed each time examples are shifted in a new spec. Diff will be cleaner with file prefix.

Let's do this after #13676

Data already exists in this package https://github.com/wooorm/commonmark.json, we can use it.

create-gfm-fixtures can be useful too.