Documentation: singlefile headless=false mode

### What is the URL of the page you'd like to see improved?

https://github.com/ArchiveBox/ArchiveBox/wiki/Chromium-Install

### What is the title of the relevant section?

Docker VNC Setup

### What is the suggested edit?

Hello! In several places you [mention](https://github.com/ArchiveBox/ArchiveBox/issues/746#issuecomment-2578562957) the "headfull" mode. However there are no instructions on how to enable that mode for the archivebox itself. Only how to start the chromium alone to login to websites before starting the service. It was non trivial to deduce that I have to change not only the option in ArchiveBox config (`CHROME_HEADLESS`), but also the options for singlefile-cli. To make matters worse singlefile-cli does not have its options listed in its README. I understand that currently there is major refactoring underway and the whole wiki may be significantly changed, as well as that in the future there might be less value in keeping the chromium "headfull", but I think it still makes sense to add the instructions on how to do that to wiki. After all it may be just cool to look how the pages are being archived in real time and useful for some debugging. Thanks!

P.S. Relevant ArchiveBox config option:
```
SINGLEFILE_ARGS = ["--browser-headless=false"]
```