Support for page references without title

[eXpl0it3r]

Currently it seems like Literate Nav doesn't support specifying a dedicated markdown page, while not providing a title, i.e. letting the title to be inferred. This works fine if you use a wild-card.

Works:

- [Home](index.md)
- Test
    - test/*.md

Doesn't work:

- [Home](index.md)
- Test
    - test/page2.md
    - test/page1.md

Workaround 1:

- [Home](index.md)
- Test
    - test/page2*.md
    - test/page1*.md

This works, but runs the risk of accidentally matching some other page.

Workaround 2:

- [Home](index.md)
- Test
    - [Page 2](test/page2.md)
    - [Page 1](test/page1.md)

The use case behind this is, that I don't want the pages sorted alphabetical, as such I can't use a wildcard. But now I'd have to specify the title for each page, instead of the title being automatically inferred from the page title.

I guess one alternative option would be to generate the navigation, but not sure I'd gain much compared to just manually listing things.