Consider offering offer downloadable full-site PDFs

### Contributions

- [x] I have read the contribution docs, and understand what's expected of me.

### Link to the page on docs.getdbt.com requiring updates

[Raised in dbt community slack](https://getdbt.slack.com/archives/C0441GSRU04/p1745917116001159) -- dbt user asked if it was possible to have the docs offline as they experienced a blackout during their dbt learning.

## options
there are possible ways to do/offer this via engineering efforts:
- per-page PDF with browser’s print function + print styles
- add a small print button on each docs page (optional).
- we should ensure the docs site has a clean [@media print](https://developer.mozilla.org/en-US/docs/Web/CSS/@media/print) stylesheet.
- users can hit "Print to PDF" on any page.

- use [docusaurus-plugin-pdf (unofficial but low-effort)](https://github.com/jean-humann/docs-to-pdf)
- add a “Download full docs PDF” link somewhere on the site.

### What part(s) of the page would you like to see updated?

N/A

### Additional information

_No response_