Update README [skip travis]

point to gpoiod project, add compose example

README.md

@@ -191,7 +191,9 @@ Disadvantages of the native GPIO support are:
   3. Replace all native gpio nodes with `pi gpiod` nodes.
   4. Configure `pi gpiod` nodes to connect to `PiGPIOd daemon`. Often the host machine will have an IP 172.17.0.1 port 8888 - but not always. You can use `docker exec -it mynodered ip route show default | awk '/default/ {print $3}'` to check.
 
-For detailed install instruction please refer to the `node-red-node-pi-gpiod` [README](https://github.com/node-red/node-red-nodes/tree/master/hardware/pigpiod#node-red-node-pi-gpiod)  
+For detailed install instruction please refer to the `node-red-node-pi-gpiod` [README](https://github.com/node-red/node-red-nodes/tree/master/hardware/pigpiod#node-red-node-pi-gpiod)
+
+If you want to run gpiod in a container rather than on the host, then [this project](https://github.com/corbosman/node-red-gpiod) may help.
 
 
 ## Managing User Data
@@ -274,10 +276,7 @@ services:
     networks:
       - node-red-net
     volumes:
-      - node-red-data
-
-volumes:
-  node-red-data:
+      - ~/node-red/data:/data
 
 networks:
   node-red-net:
@@ -289,7 +288,7 @@ The above compose file:
 - sets the timezone to Europe/Amsterdam
 - Maps the container port 1880 to the the host port 1880
 - creates a node-red-net network and attaches the container to this network
-- persists the `/data` dir inside the container to the `/mnt/docker-cluster/node-red/data` dir outside the container
+- persists the `/data` dir inside the container to the users local `node-red/data` directory. The `node-red/data` directory must exist prior to starting the container.
 
 ## Project Layout
 This repository contains Dockerfiles to build the Node-RED Docker images listed above.
@@ -431,6 +430,28 @@ Then a simple flow like below should work - using the alias *broker* we just set
 This way the internal broker is not exposed outside of the docker host - of course
 you may add `-p 1883:1883`  etc to the broker run command if you want to see it...
 
+### Docker-Compose linking example
+
+Another way to link containers is by using docker-compose. The following docker-compose.yml
+file creates a Node-RED instance, and a local MQTT broker instance. In the Node-RED flow the broker can be addressed simply as `broker` at its default port `1883`. 
+
+```
+version: "3.7"
+
+services:
+  node-red:
+    image: nodered/node-red
+    restart: unless-stopped
+    volumes:
+      - /home/pi/.node-red:/data
+    ports:
+      - 1880:1880
+
+  broker:
+    image: eclipse-mosquitto
+    restart: unless-stopped
+```
+
 
 ## Common Issues and Hints