Make the docker widget's sock-path an Array

### Description

Having multiple docker servers would require me to make multiple widget of `docker-containers`, although that's good and all but when I need them to appear in a single tab instead of multiple would not be possible at the moment since each widget will be treated as 1 tab. Turning `sock-path` property into a list of `sock-path` would most likely solve this.

```yml
- type: docker-containers
title: Docker
cache: 1s
sock-path:
- http://docker-proxy1.domain
- http://docker-proxy2.domain
#....
```

Though I'd imagine that this would create complexity to the widget if for example one of the socket proxy is down.