Page numbers in table of content (PDF) are off by 2

[rsasse]

The compiled PDF at https://tamarin-prover.github.io/manual/tex/tamarin-manual.pdf states on page 3 (Contents) that the introduction starts on page 5. Clicking it leads to the introduction, but that is on page 7. So, the link works correctly, but the numbers shown in the TOC are off by 2.

The same happens for the Installation chapter (2) and the Modeling issues chapter (8), so this is throughout the document.