Several parts of this are not ideal yet
- Frontmatter close should show the open and show the EOF, instead of
pointing at the open
- Trailing content on close will usually have a newline
- Multiple frontmatters should show the original frontmatter
- Some content, like supported infostrings, should go in a help
- Ideally we try to recover on no closing and instead point out a
mismatched open/close
But this is still an improvement over nothing!
