### Bug description

[Here](https://quarto.org/docs/reference/formats/html.html#format-options) is an example of a webpage which is confusing to read. Once someone becomes more comfortable with Quarto, it's hard to tell if a command is specifically for _quarto.yml, specifically for index.qmd or about.qmd, a yaml (say in doc xxx.qmd), a subsection (in xxx.qmd), or _publish.yml.

- For example, _I may want to set my figures in my HTML webpage xxx.qmd to centred_. The linked website + image make it hard to know if these are commands to use in the **\!\[\]()** or the **yaml.**

This is more of a stylistic choice for simplifying communication, but it is such a barrier to using Quarto that it kind of is a bug. 

- For example, if the keys were even colour-coded rather than just purple, that might help users know which commands were for a yaml, for which doc type, or if they are feature-specific (in text only). Thanks so much!

<img width="788" alt="Screenshot 2023-04-29 at 10 16 36 AM" src="https://user-images.githubusercontent.com/81820608/235307560-6f55879b-cd8e-4c96-ba5f-5af9098b519c.png">

**System Info**
- Mac OS
- R version 4.2.2 (2022-10-31)

**Quarto Check**
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.1: OK
      Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.3.326
      Path: /Applications/quarto/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.9.13 (Conda)
      Path: /Applications/anaconda3/bin/python
      Jupyter: 4.11.2
      Kernels: python3, ir

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
      Version: 4.2.2
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.2/Resources/library
      knitr: 1.42
      rmarkdown: 2.21

[✓] Checking Knitr engine render......OK

### Checklist

- [X] 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.
- [X] 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.
- [X] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
cwickham
2023-04-29T14:28:28Z
sophiestrazie
documentation
v1.4
open
UX Issue: Keys Not Labeled
https://github.com/quarto-dev/quarto-cli/issues/5352