I think that saving small example datasets a directory of your choice (eg data/) within a package is fine. And CSV is a great choice, since for small datasets size and other considerations (like reading time, ability to mmap, etc) not very significant compared to the advantages (simplicity, transparency, lightweight dependencies).
For certain kinds of data,
https://docs.julialang.org/en/v1/stdlib/DelimitedFiles/
may be enough, too.
You can then define a path lookup function in your package.