Unity 2020.3.31f1, Windows 10.

Is it possible to use local documentation, e.g. HTML files in the Assets folder of a project, as the Help URL for a component?

If so, what path should I put in the HelpURL annotation?

I tried the following annotations with a file at Assets/Documentation/Test.html, but all of them led to the same behavior of nothing happening when I click the help icon for the component in the inspector:

[HelpURL("Assets/Documentation/Test.html")]
[HelpURL("/Assets/Documentation/Test.html")]
[HelpURL("../Documentation/Test.html")] // relative path to script
[HelpURL("file://Assets/Documentation/Test.html")]
[HelpURL("file:///Assets/Documentation/Test.html")]
[HelpURL("Documentation/Test.html")]
[HelpURL("/Documentation/Test.html")]
[HelpURL("file://Documentation/Test.html")]
[HelpURL("file:///Documentation/Test.html")]

I couldn't think of anything else.

If this isn't possible, then how is component documentation usually distributed with a package? Is it always distributed online? But then, what if hosting it online isn't appropriate or feasible?