The warning, printed before running `docker system prune` was printing the
filters in JSON format.
This patch attempts to make the output human readable;
- updating the code, and template to print filters individually
- reducing the indentation (which was quite deep)
Before this patch was applied;
```
docker system prune --filter until=24h --filter label=hello-world --filter label!=foo=bar --filter label=bar=baz
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all dangling images
- all dangling build cache
- Elements to be pruned will be filtered with:
- label={"label":{"bar=baz":true,"hello-world":true},"label!":{"foo=bar":true},"until":{"24h":true}}
Are you sure you want to continue? [y/N]
```
With this patch applied;
```
WARNING! This will remove:
- all stopped containers
- all networks not used by at least one container
- all dangling images
- all dangling build cache
Items to be pruned will be filtered with:
- label!=foo=bar
- label!=never=remove-me
- label=bar=baz
- label=hello-world
- label=remove=me
- until=24h
Are you sure you want to continue? [y/N]
```
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
26e004797b