docs: ✨ align table colwidths on reference index page

[signekb]

Description

This PR customises the summarize function for layout.Sections by adding column widths to the tables.
This change only affects the tables created on the reference index page.

Full disclosure: I don't really like the way the render and summarize function(s) are set up in quartodoc, but I kept it as close to the original as possible (basically only adding the + ': {tbl-colwidths="[40,60]"}' in L70 here).

An alternative solution would be to change the output directory of quartodoc to e.g., out_index: docs/reference/index-quartodoc.qmd and then add a custom index page docs/reference/index.qmd that looks something like this:

---
tbl-colwidths: [40,60]
---

{{< include /docs/reference/index-quartodoc.qmd >}}

Effect of this PR

Before/current	After

Closes #946

This PR needs an in-depth review.

Checklist

• Updated documentation
• Ran just run-all

[lwjohnst86]

Yea, I don't love how quartodoc is internally implemented, but this looks fine with me 😁 we aren't building quartodoc, and it isn't high priority to make elegant, well designed code for it. Just whatever works 😛