Add shl server volume

Author: daniellrgn

docker-compose.yml

@@ -6,6 +6,8 @@ services:
     ports:
       # allow override of published port
       - "127.0.0.1:${EXTERNAL_PORT:-9000}:8000"
+    volumes:
+      - shl-server-data:/app/db
   client:
     build: ./client
     ports:
@@ -15,4 +17,7 @@ services:
     ports:
       - "127.0.0.1:${EXTERNAL_PORT:-9002}:3000"
     env_file:
-      - ui/app.env
+      - ui/app.env
+
+volumes:
+  shl-server-data: {}