Add Dockerfile for mdbook

.dockerignore

@@ -9,3 +9,5 @@
 !/Cargo.lock
 !/Cargo.toml
 !/ascii_art.txt
+!/docs
+!/book.toml

Dockerfile.mdbook

@@ -0,0 +1,13 @@
+FROM rust:slim AS builder
+
+WORKDIR /app
+
+RUN cargo install mdbook
+
+COPY book.toml /app/book.toml
+COPY docs /app/docs
+
+RUN mdbook build
+
+FROM nginx:alpine AS webserver
+COPY --from=builder /app/book /usr/share/nginx/html