The default page (index.html) displayed by the PlDoc generator is not the one you want

PlDoc pages can be created using

swipl --pldoc <file name>.pl

The page is then made available on an Internet browser.

However the default page displayed is index.html when the page you are probably wanting to see is the HTML documentation for <file name>.pl.

To get from index.html to the HTML documentation for <file name>.pl click on the file name link in index.html, e.g.