Is `--builder=singlehtml` deprecated?

Describe the bug

"singlehtml" does not work as a --builder arg.

To Reproduce

Steps to reproduce the behavior:

% jupyter-book build --builder singlehtml notebook.ipynb

Error: Invalid value for '--builder': invalid choice: singlehtml. (choose from html, dirhtml, pdfhtml, latex, pdflatex, linkcheck, custom)

Expected behavior

I expected "singlehtml" to be a --builder option. Or for references of "singlehtml" to be removed form the docs.

Environment

• Python Version [e.g. 3.7.1]: 3.9.5
• Package versions or output of jupyter-book --version:

  Jupyter Book      : 0.11.2
  External ToC      : 0.2.2
  MyST-Parser       : 0.13.7
  MyST-NB           : 0.12.3
  Sphinx Book Theme : 0.1.1
  Jupyter-Cache     : 0.4.2
  NbClient          : 0.5.3
  

• Operating System: CentOS Stream release 8

Additional question

Are there any other methods to create a stand alone HTML file (with CSS and JS in the header)?

[choldgraf]

I think we could just add a "singlehtml": "singlehtml" line here and it should work as expected…that is worth trying!

[choldgraf]

Hmmm - singlehtml should be an option as well! Can you link to the docs where this is mentioned?

(and note that per your question, this won’t put everything in the header, it’ll still create a bundle of assets for the output)