Ensure yaml strings correctly handled

Ensure yaml strings are correctly handled, and display the rendered template in a better way for the user to copy it.

For instance if the string value is `--rm -it \\n eunomie/scout-cli` this should be rendered to the user as

```
docker run --rm -it \
eunomie/scout-cli
```

Even is the newlines are removed from the string to be executed.

See https://yaml-multiline.info