Update volume mount and enable shell debug mode

Changed the Docker volume mount to map ./data to /app/instance instead of /app/data in docker-compose.yaml. Also enabled shell debug mode in entrypoint.sh by adding the -x flag to 'set -e' for easier troubleshooting.

docker-compose.yaml

@@ -6,4 +6,4 @@ services:
     ports:
       - "5000:80"  # change if needed
     volumes:
-      - ./data:/app/data  # maps host ./data to container /app/data
+      - ./data:/app/instance  # maps host ./data to container /app/data

entrypoint.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-set -e
+set -ex
 
 echo "Running database migrations..."
 flask db upgrade