Show release and record package fields on schema page

[duncandewhurst]

The pagination extension patches release-schema.json, release-package-schema.json and record-package-schema.json but only the fields in release-schema.json are shown on the schema page.

We should display fields from all schemas patched by an extension.

[jpmckinney]

This only affects the pagination extension. With 1.2, packaging is set to change, and there's a good chance pagination (or at least links like in JSON Hyper-Schema) will be made part of OCDS open-contracting/standard#928.

As such, extending packages will be a thing of the past. I'm okay with one extension being badly displayed until 1.2, after which it won't matter. In the meantime, the pagination readme is clear enough.