ADD default .env file as a fallback
ADD default .env file as a fallback

If a repository contains a `.env` example file or - in case of a private repository - a `.env` file with production values,
a developer can add a local (e.g. `.env.local` file to `.gitignore`) and feed it to `env-cmd`.
So in development a custom local configuration can be used, but in production, `env-cmd` falls back to `.env`
toddbluhm/env-cmd,toddbluhm/env-cmd