docs: Star website: API index page for pg-sql2 has no content
### Feature description

API index page at https://star.graphile.org/pg-sql2/api/ has no content but ~is~ will be linked to from other documentation sites

<!-- Please describe the feature you'd like to see in as much detail as you
      can. -->

### Motivating example

<!-- What motivated this feature request? Why is this feature useful to other
      people? What other use cases can you think of for it?  -->
Linked to from https://postgraphile.org/postgraphile/current/make-extend-schema-plugin

### Breaking changes

<!-- If this feature requires breaking changes, detail them here, otherwise
      delete this section -->
NA

### Supporting development

I [tick all that apply]:

<!-- To tick a checkbox, change it from `[ ]` to `[x]` -->

- [x] am interested in building this feature myself
- [x] am interested in collaborating on building this feature
- [x] am willing to help testing this feature before it's released
- [ ] am willing to write a test-driven test suite for this feature (before it exists)
- [ ] am a [Graphile sponsor](https://www.graphile.org/sponsor/) ❤️
- [ ] have an active [support or consultancy contract](https://www.graphile.org/support/) with Graphile
- [x] I am the other half of the Graphile maintainer team 😉 
