fix: fixed docker-compose.yml and renamed gdal_rio.env to .env.example

[JinIgarashi]

@iferencik please review these changes

• switched ENV to ARG in Dockefile, so these variables can be passed do docker from environmental variables correctly.
• renamed gdal_rio.env to .env.example (you need to do cp .env.example .env first)
• fixed docker-compose.yml.
  • spacified platform, so it can work with MacOS, too
  • deleted container name from yaml
  • delete unnecessary environment settings