Updated README with troubleshooting details regarding the Docker daem…

…on running as root

Resolves #5

README.md

@@ -156,4 +156,27 @@ cd multipaper-docker
 docker build --target master -t multipaper-master .
 # Build the Multipaper server image
 docker build --target server -t multipaper .
-```
+```
+
+## Troubleshooting
+
+### World files are not being generated by the server
+
+On many systems the Docker daemon runs as root. If the directories being mounted to your containers don't exist, they will be created by Docker.
+
+MultiPaper processes within these containers do not run as the root user and therefore may be unable to write files into any directories created by the Docker daemon.
+
+If you find that your generated world files are not being synced to the `master` directory, please ensure that the directory is **not** owned by `root`.
+
+Alternatively, you may add the following line to the `master` service to specify that application processes should run as `root` inside the container.
+
+```yaml
+  master:
+    container_name: master
+    image: noevidenz/multipaper-master:latest
+    user: root # this line sets the user inside the container
+    ports:
+      - 25565:25565 # Opens the proxy port
+    volumes:
+      - ./master:/app # Required to access world files
+```