Support add extra static files dir

[dingbo8128]

I have some builed mdbooks that I want to host on my site, but I don't kown how to let kobweb kown them.
I want to visit them using url like : https://myside.com/books/kotlin-book-xx

[bitspittle]

I moved this over to Discussions, because I don't think as written it's a proper issue, but it seems like more a question. Unfortunately, I don't know much about mdbooks, so I think it will be up to you or someone else to come up with clear, obvious repro steps for the issue you are having.

In case it is relevant, please review https://kobweb.varabyte.com/docs/concepts/foundation/project-structure#public-resources and maybe also https://kobweb.varabyte.com/docs/guides/generating-code#generating-resources

[dingbo8128]

This problem has nothing to do with mdbook at all. A built mdbook is just a bunch of static files.
The core of the problem is how I can add additional static resource paths when using Kobweb. If I were using Ktor directly, I'd know how to do it. Now that Kobweb has Ktor built - in, I'm not sure how to proceed.