Missing requirement on `plantuml` binary package

[schuylermartin45]

Description

Apologies that this is coming in as a bug. I cannot seem to select this as a documentation issue. I assume someone else has the ability to change the type after submission.

As outlined in the discussion coming from #3942 and https://github.com/nlohmann/json/pull/4024, as someone who is trying to contribute to the documentation for the first time, it is not clear that plantuml is a depedency required to run the documentation engine.

In order for me to run the mkdocs instance for the first time, I needed to brew install plantuml on my Mac or sudo apt install plantuml on my Ubuntu machine. The README discussing how to run the mkdocs project does not mention this requirement.

I see this as a documentation issue first, but arguably we could add a make directive to or have some other mechanism to ensure the required dependency is installed to the system attempting to run the documentation server.

Reproduction steps

1. Fork and Clone this project for the first time
2. Attempt to run the make install_venv serve -C docs/mkdocs command, as described in the docs/README.md file
3. Expect this to fail if you do not have the plantuml MacOS/Debian/etc package installed previously on your system

Expected vs. actual results

If the docs suggest that all I need to do is run a make command to start the documentation server, I would expect that is all I need to do as a new contributor to the project. This caused some confusion and a potential waste of everyone's time trying to debug something minor.

Minimal code example

No response

Error messages

No response

Compiler and operating system

MacOS/Linux

Library version

development

Validation

• [X] The bug also occurs if the latest version from the develop branch is used.
• [ ] I can successfully compile and run the unit tests.

[schuylermartin45]

And shout out to @JeanChristopheMorinPerso for helping me figure this issue out.

[nlohmann]

I think this can be fixed by adding a remark to the documentation.