Clarify GitHub Actions layout within /home/runner/work

Author: holta

.github/workflows/10min-iiab-unittest-ubuntu.yml

@@ -36,6 +36,7 @@ jobs:
           uname -a    # uname -srm
           whoami      # Typically 'runner' instead of 'root'
           pwd         # /home/runner/work/iiab/iiab == $GITHUB_WORKSPACE == ${{ github.workspace }}
+          # tree /home/runner/work/_actions /home/runner/work/_temp /opt/hostedtoolcache (reusable deps; 88,000+ lines!)
           # ls -la /opt    # az, containerd, google, hostedtoolcache, microsoft, mssql-tools, pipx, pipx_bin, post-generation, runner, vsts
           # apt update && apt dist-upgrade -y && apt autoremove -y
       - name: Set up /opt/iiab/iiab    # Some steps to get ready for the install