fill in some missing history on Racket's slice of lightning
make site: propagate package dependencies, modules, etc. to catalog
meta/pkg-build: save products of failed installs

When a package installation fails in some ways, we may still
be able to "dumpster dive" for documentation that the package
managed to build.
raco pkg: fix test
raco setup: propagate doc-build error in summary and exit status
meta/pkg-build: detect conflicts among packages with documentation

Two packages might install documentation under the same name, or the
same executable, and so on.