Develop PDF template and styling

We generate our PDFs using [Typst](https://typst.app/)

At present I've created a minimal template in `pdf/template/template.typ`. This template contains some placeholder content to demonstrate the Template.

Over time we can evolve this template to create PDFs of our manuals that fit well with our brand identity. The Typst website has a [guide](https://typst.app/docs/tutorial/making-a-template/) for creating templates. The five default Templates that ship with Typst are also [available](https://github.com/typst/templates) for reference.

Typst is a new project but is seeing widespread adoption so new templates are appearing regularly on GitHub. For example the well-known 'Orange Book' LaTeX template has been [ported](https://github.com/flavio20002/typst-orange-template) to Typst.

There's also lots of resources on the regularly updated [Awesome Typst](https://github.com/qjcg/awesome-typst) list.

Start with pdf/template/template.typ and the linked Typst template guide, then compare the default Typst templates and Orange Book reference. Define a consistent branded style for the manuals and evolve the template until it produces a cohesive PDF rather than placeholder content.

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