Show escaping of quotes in example

I think it'd be useful to show how to escape quote marks in the CSV (i.e., double quotes within quote demarcations).

```
3,"But, I wonder, how to include ""quote mark,"" if possible, ""as they say""",[use a double quote to escape](https://gpdb.docs.pivotal.io/6-5/admin_guide/load/topics/g-escaping-in-csv-formatted-files.html)
```