Document Typst partials with other partials

[cwickham]

Adds Typst Partials: Preview
Closes quarto-dev/quarto-cli#8500

[github-actions]

🚀 Deployed on https://deploy-preview-1202.quarto.org

[gordonwoodhull]

To my knowledge, looks correct and helpful!

[cderv]

If that can help check correct understanding, we do document a bit those partial in our skeleton for someone when creating a typst format extension

From https://github.com/quarto-dev/quarto-cli/blob/e8c3cbf43a0217c7d4a2afc31b3ee42c5b37db09/src/resources/create/extensions/format-typst/_extensions/qstart-filesafename-qend/typst-template.typ#L2-L12

// This is an example typst template (based on the default template that ships
// with Quarto). It defines a typst function named 'article' which provides
// various customization options. This function is called from the
// 'typst-show.typ' file (which maps Pandoc metadata function arguments)
//
// If you are creating or packaging a custom typst template you will likely
// want to replace this file and 'typst-show.typ' entirely. You can find
// documentation on creating typst templates and some examples here:
// - https://typst.app/docs/tutorial/making-a-template/
// - https://github.com/typst/templates

From https://github.com/quarto-dev/quarto-cli/blob/e8c3cbf43a0217c7d4a2afc31b3ee42c5b37db09/src/resources/create/extensions/format-typst/_extensions/qstart-filesafename-qend/typst-show.typ#L1-L13

// Typst custom formats typically consist of a 'typst-template.typ' (which is
// the source code for a typst template) and a 'typst-show.typ' which calls the
// template's function (forwarding Pandoc metadata values as required)
//
// This is an example 'typst-show.typ' file (based on the default template
// that ships with Quarto). It calls the typst function named 'article' which
// is defined in the 'typst-template.typ' file.
//
// If you are creating or packaging a custom typst template you will likely
// want to replace this file and 'typst-template.typ' entirely. You can find
// documentation on creating typst templates here and some examples here:
// - https://typst.app/docs/tutorial/making-a-template/
// - https://github.com/typst/templates

[github-actions]

Successfully created backport PR for prerelease:

• [Sync to prerelease] Document Typst partials with other partials #1227