Explain the need to update the test directory structure in `usethis-p…#1379

nathanjmcdougall merged 1 commit intomainusethis-python/usethis-python:mainfrom

1378-update-the-usethis-python-module-layout-modify-to-explain-tests-src-parallelismusethis-python/usethis-python:1378-update-the-usethis-python-module-layout-modify-to-explain-tests-src-parallelismCopy head branch name to clipboard