How do I access the License API thru here?

Hello, according to Github API docs, you need to attach `application/vnd.github.drax-preview+json` in the `Accept` header. Once that is supplied, one should get the license info along with the repo object. However, I tried the following:

```
const gh = new Github({
username: 'xxxx',
password: 'xxxxxx'
}, '', 'application/vnd.github.drax-preview+json').search()
```

but to no avail. How can I access the License API using this package? Thanks in advance

先檢視 issue 中所示的 Github 建構函式與 search() 呼叫，接著將該 package 的 request 與 header 處理方式和 GitHub License API 文件進行比較。當此 package 能透過文件所述的 API 流程存取授權資訊，且支援的使用方式已清楚說明時，工作就完成了。

由索引模型根據 Issue 內容生成。