Support new Output

In order to support new output types you need to:

1. Add the required plugin gem to the Gemfile
2. Add the new supported type to the start.sh script
3. Write a new output file following the plugin’s documentation, e.g. output-s3.conf. Ideally just keep the plugin required variables.
4. Update start-container.sh
5. Update docs:
   • Create a new document, e.g. CONFIGURE_S3
   • Add the new output type to CONFIGURE_LOG_EXPORT_CONTAINER.md
   • Update docker-compose.yml

IMPORTANT: Please test your changes through the process