Entries listed here will be appended to the meta.outputsToInstall attribute for each package in environment.systemPackages, and the files from the corresponding derivation outputs symlinked into /run/current-system/sw.
For example, this can be used to install the dev and info outputs for all packages in the system environment, if they are available.
To use specific outputs instead of configuring them globally, select the corresponding attribute on the package derivation, e.g. libxml2.dev or coreutils.info.