Per Gwen Shapira's comment during the AK 2.6.0 RC2 vote:
There were two sitedoc files - 2.12 and 2.13, we don't really need two
sitedocs generated. Not a big deal, but maybe worth tracking and fixing.
During the release, we're publishing site-docs for both 2.12 and 2.13, but we really don't need both. For example, in AK 2.6.0 we published:
Ideally we would change the build to avoid producing the site-docs for both Scala versions.