Remove -d from Compose command

Signed-off-by: Ben Firshman <ben@firshman.co.uk>

README.md

@@ -19,7 +19,7 @@ Running
 
 Run in this directory:
 
-    $ docker-compose up -d
+    $ docker-compose up
 
 The app will be running on port 5000 on your Docker host, and the results will be on port 5001.