handbook/docs/beyond_basics/_examples/DL-101-179-109

$ git config -f .gitmodules --replace-all submodule.midterm_project.url https://github.com/datalad-handbook/midterm_project
$ datalad save -m "SERVICE COMMIT - IGNORE. This commit only serves to appropriately reference the subdataset in the public showroom dataset"
add(ok): .gitmodules (file)
save(ok): . (dataset)