Re: [web-annotation] Absolute or relative URI's in examples

Yeah. Think that should.

I'd wondered about doing the same for the JSON-LD examples, but it's some
pretty heavy cruft because `@base` isn't top level (afaik), so it ends up
looking like:
```json
{
  "@context": {
    "@base": "http://example.com/"
  }
}
```
http://www.w3.org/TR/json-ld/#base-iri

Also...
> Please note that the @base will be ignored if used in external contexts.

Which is kind of sad...but also makes sense.