Put a link to the Team Leave Appscript in the Taking Time Off page

[the appscript link
](https://script.google.com/d/1jg-GNvq7bYsLqYT7YvmiczTwFZVLMDBJYeahM7qCWxVx_Dpe8stvR5kf/edit?usp=sharing)

so we can find this in our docs and not by reading closed GH issues 