doc: Add instructiosn to switch networks and volumes

docs/switch-networks.md

@@ -0,0 +1,29 @@
+# Switch networks when using Docker Compose
+
+When running Marlowe starter kit, there are three different networks to use alongside the `NETWORK` environment variable: preview, preprod, and mainnet. 
+
+Stop the running containers with:
+
+```
+$ docker-compose down
+```
+
+Notice the containers are removed although the volumes are not removed. List the volumes by:
+
+```
+$ docker volume ls
+```
+
+This is generally desirable because it allows running the starter kit on the same network with significantly less sync time in the future.
+
+However when switching networks without removing the volumes, the logs will show a network mismatch. The example below shows an attempt from switching between preprod to preview.
+
+```
+marlowe-starter-kit-node-1           | NetworkMagicMismatch "/data/db/protocolMagicId" (NetworkMagic {unNetworkMagic = 1}) (NetworkMagic {unNetworkMagic = 2})
+```
+
+Remove the associated volumes by passing the volume flag. If the container is still running, the force flag (`-f`) may be needed as well to remove the volume.
+
+```
+docker-compose down -v
+```