This makes sure that empty lines in lint examples are preserved.
It also fixes the documentation for the invalid_ref lint, which was not
shown because of an extra newline before the lint declaration.
- Section IDs, with handy anchor links
- Multiple filters for levels
- Table rendering, block quote size
- Nicer loading (hide un-rendered content)
- Code highlighting (only for Rust, of course!)
- Fix parsing of descriptions that have a newline after the section
title (lead to duplicating the title, e.g., "Examples", in the
content)
