### Bug description

`header-includes` is not explicitely documented, although it is used on https://quarto.org/docs/reference/formats/pdf.html . It is also wrongly mentioned on https://quarto.org/docs/output-formats/pdf-basics.html (the actual code uses `include-in-header`).

Maybe `header-includes` is deprecated in favor of the `text:` subkey of `include-in-header`? Then is it possible to specifiy both include files and literal text?

My use case is that I specify a `preamble.tex` file with `include-in-header`, but I also need to add an extra header line that doesn't belong in the preamble file (the preamble is generic while the one-line fix is specific to this project). It's possible but a bit messy to make another `.tex` file just for the one-line fix, and if I already give a `preamble.tex` file to `include-in-header` then I don't think I can use the `text:` subkey.

### Checklist

- [ ] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [ ] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [ ] Please document the operating system you're running. If on Linux, please provide the specific distribution.
cscheid
2022-09-22T10:03:47Z
knuesel
documentation enhancement
v1.2
closed
include-in-header / header-includes confusion
https://github.com/quarto-dev/quarto-cli/issues/2547