I looked everywhere but could not find out how to report a documentation issue. In this case a broken link…
I even had trouble selecting a Category to write this: Documentation, Reference, Website, Other nothing worked 
Please point me in the right direction
What is the link that is broken?
Click on “can be found here”
Not particularly vital, just reminded me it’s handy maybe to have a “anything wrong with this page” link
The staging docs site is not currently used or maintained. You should use the current documentation instead:
https://docs.particle.io/reference/device-os/api/preprocessor/preprocessor/