H2 section duplicated anchors

[froggleston]

The recent update to pkgdown (from 2.0.9 to 2.1.0) has resulted in a feature that we cannot get around without removing our core translation feature for section headings (h2) from the Workbench: r-lib/pkgdown#2737

Note, this is not the same as the CrowdIn translations but the translation of lesson specific sections, e.g. “Key Points”, etc

Until pkgdown developers add support for choosing which elements to apply anchors to, or us removing the translation support for h2 anchors, or perhaps moving these anchor translations into pkgdown (which would split our translation code), our tests will fail. Lessons continue to build successfully but have the rather confusing double link icon for each H2 section.