feat!: Separate www into www/blog and www/private

Now the private content is stored as a git submodule.
This means I can keep that repo's source private, but still use it in
the build product.
The build product (website) relies on HTTP basic authentication, so
access control is maintained throughout the SDLC.

book.toml

@@ -3,9 +3,6 @@ title = "The Bin"
 authors = ["Matthew Binning"]
 language = "en"
 
-[build]
-build-dir = "blog"
-
 [output.html]
 default-theme = "rust"
 smart-punctuation = true