A bunch more info on how to use this repo.
Added some hints for things to try.
Added a link to the Docker documentation.
Renamed to python-app from flask-app.
Moved language containers to a dedicated folder.
Tweaked so the container runs to a shell.
Updated Compose version.
Simplified FROM to default Alpine.
Adding more languages.
Removed '3' as it's now the default.
Options for stable/edge version.