Explain how to require @graphile/postgis in library mode with CommonJS

Hi, I'm not sure if this is the right place to ask such a question but I do apologies in advance.

but doing the following in my code:
```js
const PostgisPlugin = require("@graphile/postgis");
...
const postgraphileOpt = {
watchPg: true,
retryOnInitFail: true,
graphiql: true,
enhanceGraphiql: true,
graphiqlRoute: "/schema",
enableCors: true,
disableQueryLog: true,
appendPlugins: [ConnectionFilterPlugin, PostgisPlugin]
};
```
produced this error:
```sh
$ Error: Option 'appendPlugins' should be an array of functions, found 'object' at index 1 ...
```

May I know if I'm doing it completely wrong or should I not have used it within the library but in the CLI instead?