Fix typo by adding ternary statement to ejs template

[acopperlily]

This small change allows us to differentiate between 1 thing left and multiple things left. For instance, the todos view page will now render "User has 1 thing left to do" instead of "User has 1 things left to do."

The page still renders "User has 2 things left to do" and "User has 0 things left to do."