How to run swaggerui docker

The [instruction](https://github.com/swagger-api/swagger-ui/blob/master/docs/usage/installation.md#docker) 
for mounting is confusing so adding extra info on how to run it

1. Download `swagger-ui` [Docker image](https://github.com/swagger-api/swagger-ui/blob/master/docs/usage/installation.md#docker)

```bash
docker pull swaggerapi/swagger-ui
```

1. Make sure you're in the directory that contains `swagger.json`

1. Start Nginx on port `80`

```bash
# detach mode
docker run --name swagger -d -p 80:8080 -e SWAGGER_JSON=/app/swagger.json -v "$(pwd)":/app  swaggerapi/swagger-ui
```

```bash
# it will look like the command hangs but if there's no error then it's working -___-
docker run -p 80:8080 -e SWAGGER_JSON=/app/swagger.json -v "$(pwd)":/app  swaggerapi/swagger-ui
```

1. Go to browser and access `http://localhost:80`