Warning when installing grid-list from npm

## Scenario

```gherkin
Given I add grid-list to my package.json file
When install it
Then I get the warning "npm WARN package.json grid-list@0.1.0 No repository field."
```

## Solution

- [x] add the repo field in `package.json`

https://www.npmjs.org/doc/files/package.json.html#repository