### Bug description

When you add [custom appendix sections](https://quarto.org/docs/authoring/appendices.html#custom-appendix-sections) to a post, the headings for these sections are not given an anchor. I believe this is a bug, as other non-custom sections such as citation are given an anchor.

You can see this behaviour in this [blog post](https://blog.djnavarro.net/posts/2022-04-20_porting-to-quarto/#footnotes-1). The sections provided by Quarto have anchors, but the custom "Last updated" and "Details" sections do not. The difference is that the headings for the former section have the `anchored` class, but the latter do not.

Adding the `anchored` class manually while creating an appendix section does not work well either, as the anchor gets put at the end of the section, rather than beside the heading.

```md
## Acknowledgments {.appendix .anchored}

I am grateful for the insightful comments offered by the anonymous peer reviewers at Books & Texts. The generosity and expertise of one and all have improved this study in innumerable ways and saved me from many errors; those that inevitably remain are entirely my own responsibility.
```

### 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.
dragonstyle
2022-10-30T20:06:15Z
mccarthy-m-g
bug
v1.3
closed
Custom appendix sections are not anchored
https://github.com/quarto-dev/quarto-cli/issues/3112