[Bug] auth documentation need to be updated

### Bug Type (问题类型)

rest-api (结果不合预期)

### Before submit

- [x] 我已经确认现有的 [Issues](https://github.com/apache/hugegraph/issues) 与 [FAQ](https://hugegraph.apache.org/docs/guides/faq/) 中没有相同 / 重复问题 (I have confirmed and searched that there are no similar problems in the historical issue and documents)

### Environment (环境信息)

- Server Version: 1.7.0 (Apache Release Version)
- Backend: Hstore 1 nodes, SSD
- OS: xx CPUs, xx G RAM, Ubuntu 2x.x / CentOS 7.x
- Data Size: xx vertices, xx edges

### Expected & Actual behavior (期望与实际表现)

文档中描述创建用户组的接口例子是
`POST http://localhost:8080/graphspaces/DEFAULT/auth/groups`
实际上调用会报404
只有使用
`POST http://localhost:8080/auth/groups`
才会正确创建用户组

### Vertex/Edge example (问题点 / 边数据举例)

```javascript

```

### Schema [VertexLabel, EdgeLabel, IndexLabel] (元数据结构)

```javascript

```