additional indentation for task lists about dprint-plugin-markdown

[dsherret]

How do you feel about matching Prettier's formatting of task lists in dprint? If you agree and provide some guidance, I'm happy to take a stab at implementing this.

Yes, it does look better and that would be great.

If you want to take a look at implementing this, I think something like what's done in parse_list would need to be done for when item.marker.is_some(). Using with_indent_times(sub_items, 4) should work along with increasing and decreasing context.indent_level += 4 and context.raw_indent_level += 4.

Also, there seems to be no tests for multi-line task lists, which is probably why I never noticed this before.

Thanks for dprint! It reduces the time to format my knowledge base consisting of ~1600 Markdown files from 87 seconds (Prettier) to 0.2 seconds! 💥

Awesome! That is probably mostly the "increment": true feature, but probably even without it it would be super fast.