37 command link not found

[pedroVinko]

Link github.com/basecamp/37 from https://github.com/basecamp/handbook/blob/master/our-internal-systems.md#the-37-command is not found.

[Connor Gurney]

This is because it's a private repository and hasn't been open-sourced. This is the case with several internal tools - see #28 #51, #73, #111, #152 and #153 for examples.