I started using Workbench to write documentation again after some time off. Something must have happened (maybe upgrading to v12?), because now when I double click on a documentation page in Workbench to edit it, Mathematica beeps on startup.
Why the Beep? reports
The shared stylesheet "Wolfram/FunctionPageStyles.nb" could not be found. The default stylesheet will be used instead.
I found the required stylesheets available for download here. Where should I put them?