[Proposal] Nested books and book references

[aiden-leong]

Preface

This idea comes from Makefile. I use mdBook as a blog system, so the main book is called blog. At the same time I'm writing several independent books or documents on different topics. If I put them in a single book, the user experience won't be as good as we expect.

Proposal

SUMMARY.md

.
├── book1
│   └── SUMMARY.md
├── book2
│   └── SUMMARY.md
├── book3
│   └── SUMMARY.md
└── SUMMARY.md

We may have multiple nested SUMMARY.md. In the above case, we will generate 4 books. localhost:3000, localhost:3000/book1, localhost:3000/book2 and localhost:3000/book3. If there's no cross reference, they are just 4 books. It doesn't matter if the SUMMARY.md in the top folder uses files in sub directories.

Cross Reference

<!-- # main book‘'s SUMMARY.md -->
- [Book 1](./book1)

• If there are cross references in SUMMARY.md, generate an entry for another book.
• If the cross reference is in context, it's just a normal url, nothing special needed.

Further

We may have nested book.toml as well, but that's another topic. I don't want to cover it in this proposal.