Add Docker Compose instructions

Useful for environments where dealing with Ruby versions is a nightmare

README.md

@@ -6,6 +6,22 @@ These instructions will get you a copy of the Quarkus.io website up and running
 
 ### Installation
 
+#### Using Docker
+
+1. Install [Docker Desktop](https://docs.docker.com/install/).
+2. Fork the [project repository](https://github.com/quarkusio/quarkusio.github.io), then clone your fork.
+
+        git clone [email protected]:YOUR_USER_NAME/quarkusio.github.io.git
+
+3. Change into the project directory:
+
+        cd quarkusio.github.io
+4. Run Docker Composer
+
+        docker-compose up
+
+5. Now browse to http://localhost:4000
+#### Using a local Ruby environment
 [Jekyll static site generator docs](https://jekyllrb.com/docs/).
 
 1. Install a full [Ruby development environment](https://jekyllrb.com/docs/installation/). If you use `rvm`, run: `rvm use 2.7.1`.

docker-compose.yml

@@ -0,0 +1,9 @@
+# no version needed since 2020
+
+services:
+  jekyll:
+    image: bretfisher/jekyll-serve
+    volumes:
+      - .:/site
+    ports:
+      - '4000:4000'