[Documentation] about section and README differ on RFC

The about section states: 
```
Go package for UUIDs based on RFC 4122 and DCE 1.1: Authentication and Security Services
```

On the other hand, the README states:
```
The uuid package generates and inspects UUIDs based on [RFC 9562](https://datatracker.ietf.org/doc/html/rfc9562)
```

Suggest a change is made to the 'about' section to update the RFC reference.