Docs for highlightjsdir don't match reality

[Azhrei]

Description

The documentation for the highlightjs plugin states the following:

Valid values for the attribute highlightjsdir are:

• A URL starting with either http:// or https://,
• a local directory with an absolute path within the current project, or
• a relative directory from the project's root folder.

However, I was not able to make the third option work on macOS Sequoia 15.6 (a directory pathname relative to the project root). When I specify an absolute path, the plugin works properly. (My macOS installation is fully up to date as of this posting.)

I believe this should be a bug report for the code base, but perhaps the last option was meant to be removed and the documentation simply has not been updated? Since I'm not sure — and because I have a workaround — I decided to file this against the documentation.