Add docker-compose file for easy setup

With this, if you have docker and docker-compose installed, starting up the book is a simple matter of `docker-compose up` and then you'll find the book up at `http:\\localhost:8000` simple as that

docker-compose.yml

@@ -0,0 +1,6 @@
+web:
+  image: php:7.0-apache
+  volumes:
+    - .:/var/www/html/
+  ports:
+    - "8000:80"