No need to copy the script anywhere. Especially if you have git clone'd the repo. Just do a symbolic link to the script in question to /usr/local/bin. That way you can just do a git pull to update and no extra step to re-copy the script again.

You can also create a tiny install-script that does the symbolic link for you.

#!/bin/bash
scriptDir=$(dirname $(readlink -f $0))
sudo ln -s $scriptDir/todo.sh /usr/local/bin/

Just my two cents.

Ps. From my own perspective I wouldn't mind if you didn't call the dir 'todo.sh', ie removed the .sh at the end. This is just a personal reflection.