Unify the example emails to example.org for the sample data

This PR unify the example emails to example.org for the sample data.

```
Example domains
As described in RFC 2606 and RFC 6761, a number of domains such as example.com and example.org for documentation purposes. These domains may be used as illustrative examples in documents without prior coordination with us. They are not available for registration or transfer.
```
http://www.iana.org/domains/reserved