Fix pkgdown config for reference

[maelle]

Some topics are missing from the configuration file.

Error in check_missing_topics(rows, pkg) : 
  All topics must be included in reference index
✖ Missing topics: chembl_atc_classes, chembl_resources
ℹ Either add to _pkgdown.yml or use @keywords internal

Note that for topics you do not want to include in the index you can create an "internal" section https://pkgdown.r-lib.org/reference/build_reference.html?q=internal#missing-topics

You can also use the @keywords internal tag and redocument for, say, the package manual page.

To check all topics are listed, after editing the configuration file you can run pkgdown::check_pkgdown().

[Aariq]

We should probably set up a GH action to run check_pkgdown() at some point too.

[stitam]

Thanks @maelle, I have updated the config file and set up a GitHub Action to check_pkgdown().

[maelle]

set up a GitHub Action to check_pkgdown()

Nice! This made me open https://github.com/r-lib/pkgdown/issues/2224