Is your feature request related to a problem?

I'd like to write intro/outro parts that may not need a 3-level subdivision between part, chapter and lesson.

Currently, I need multiple levels so my introduction page maybe /getting-started/intro/about", instead of just /getting-started`. The UX is not as smooth as it could when it comes to writing proper course introductions or conclusions.

Describe the solution you'd like.

Allow having 2-levels or 1-level hierarchy.

intro
|_ _files
|_ content.md
|_ meta.md
short-part
|_ chapter-1
|__ _files
|__ content.md

Describe alternatives you've considered.

This seems a little change but I understand how this can affect UX.

• We could allow having content in parts and chapters ? Maybe have special "intro.md"/"ending.md" files ?
• Or keep content only in type "lesson", but allow a lesson to live outside of a chapter or part ? In this approach, as a default, we write lessons in a tutorial. Optionally, we can move lessons to a chapter. And optionnaly, we can move chapters into parts.
• We could instead craft independant Astro pages, and focus on linking them to specific courses via meta data? For instance adding an "outro: /some-page" field to the chapter definition or something alike. But seems convoluted, mixing the mental model of Astro and the mental model of Tutorialkit.

Additional context

The file packages/astro/src/default/utils/routes.ts seems to be responsible to route creation and could be tweaked quite easily. However such a change may have consequences on the mental model around parts/chapters/lessons in other places.