Starting point for documenting existing DNS Looking Glass endpoints.

Stephane has suggested NAPTR but this is all I have time for now. :)

I think this should be something machine-readable. For example:

```yaml
endpoints:
- http://dns.bortzmeyer.org/
- http://dns-lg.nlnetlabs.nl/
```

A very simple Python program could convert that to, say, zone master file format, etc.