Add docker stuff

Dockerfile

@@ -11,6 +11,7 @@ WORKDIR /app/book
 
 # Install honkit globally and build the book
 RUN npm install -g honkit && \
+    npm install honkit-plugin-theme-darkening --save-dev && \
     honkit build
 
 # Final Stage: Serve with Nginx

book/.gitignore

@@ -0,0 +1,2 @@
+node_modules
+_book

book/README.md

@@ -1,2 +1 @@
-# Introduction
+# Forward
-