Add empty book

The book should eventually contain all documentation that isn't suitable
for the readme or help text.

For now it's empty, but it seemed useful to add the scaffolding, so
adding to it is low friction.

type: documentation

.gitignore

@@ -1,3 +1,3 @@
 /target
 **/*.rs.bk
-notes.md
+/book/book

book/book.toml

@@ -0,0 +1,6 @@
+[book]
+authors      = ["Casey Rodarmor"]
+language     = "en"
+multilingual = false
+src          = "src"
+title        = "imdl"

book/src/SUMMARY.md

@@ -0,0 +1,3 @@
+# Summary
+
+- [Notes](./notes.md)

book/src/notes.md

@@ -0,0 +1 @@
+# Notes

justfile

@@ -42,12 +42,17 @@ lint:
 preview-readme:
 	grip -b README.md
 
+# build and serve the book
+book:
+	mdbook serve book --open
+
 # add git log messages to changelog
 changes:
 	git log --pretty=format:%s >> CHANGELOG.md
 
 dev-deps:
 	brew install grip
+	cargo install mdbook
 
 # update readme table of contents
 update-toc: