Pages without a \usage{} section show usage,NULL

[wviechtb]

Some pages do not have a \usage{} section (e.g., pkgname-package pages). Since the 2.0 update, I now see usage,NULL in the corresponding html pages.

Edit: And pages with a \usage{} section do not render the Usage properly and instead show a plain-text Usage, before the actual usage part. These problems do not show up when using bootstrap: 5 but I can't use this at the moment since this breaks some other stuff.

[maelle]

example https://pkgdown.r-lib.org/reference/pkgdown-package.html (actually this is another problem -- probably the same cause)