fix: tacc-setup.sh cloning files to wrong dir

[wesleyboar]

Overview

Clone TACC/TACC-Docs poetry files into `/user-guide/ not root (like README expects).

Related

• fixes enhance: clone TACC/TACC-Docs files directly #120

Testing

1. From root of repo, run

   rm ./{pyproject.toml,poetry.lock,user-guide/mkdocs.base.yml}
   ./bin/tacc-setup.sh

2. Verify no errors.
3. Verify these files exist:
   • ./user-guide/pyproject.toml
   • ./user-guide/poetry.lock
   • ./user-guide/mkdocs.base.yml