Update .gitignore to ignore anything in /data/ dir

[guycalledseven]

Don't know if this even qualifies as PR :) , and if this is acceptable, but I find it very useful to override few services via docker-compose.override.yml to map data dirs from containers to local volumes and put them inside ./data/ And by putting them next ./data/www/ this makes devilbox installations very compact.

eg.

  mysql:
    volumes:
      - ${DEVILBOX_PATH}/data/${MYSQL_SERVER}:/var/lib/mysql:rw${MOUNT_OPTIONS}
    user: mysql
  mongo:
    volumes:
      - ${DEVILBOX_PATH}/data/mongo-${MONGO_SERVER}:/data/db:rw${MOUNT_OPTIONS}

[cytopia]

This sounds legit