In 2e4a2a0e5a we removed the `@public` tags but the `addJadeDataDocsProcessor`
was still relying upon them being there to identify whether a doc should
be included in the public docs.
Instead we should just check for the doc not being marked with the
`@private` tag.
Closes#3212
This means that we can now run just the d.ts file generation by running:
```bash
gulp docs/typings
```
In addition the type definition generation was messing with the other docs tasks
so separating it also fixes problems there.
You can generate docs for comsumption by the angular.io website by running:
```bash
gulp docs/angular.io
```
The generated docs can be found in `dist/angular.io`