This folder is used to checkout Tsugi tools from other repositories like:
https://github.com/tsugitools/
https://github.com/tsugicontrib/
You need to include this folder in the places that Tsugi scans to look for tools
in your config.php:
$CFG->tool_folders = array("admin", "mod");
You need to edit your config.php folder to point to this folder
if you want to auto-install into this folder using the Admin UI
in Tsugi.
$CFG->install_folder = $CFG->dirroot.'/mod';
If you are installing Tsugi in a sub folder, sometimes you want the tools to be installed and served from a folder in the parent folder as in this example.
$CFG->install_folder = $CFG->dirroot.'/../mod';
$CFG->tool_folders = array("admin", "../mod");
See https://github.com/csev/py4e/ for a more complex example. You will
note that an index.php and config.php in a mod folder make it so
that when a user navigates to the /mod they are redirected
to the store.