Docs on main do not build

I have updated to the latest commit on main and it does not build:

Configuration error:
Values in 'html_sidebars' must be a list of strings. At least one pattern has a string value: '**'. Change to `html_sidebars = {'**': ['']}`.


Configuration error:
Values in 'html_sidebars' must be a list of strings. At least one pattern has a string value: '**'. Change to `html_sidebars = {'**': ['']}`.


Configuration error:
Values in 'html_sidebars' must be a list of strings. At least one pattern has a string value: '**'. Change to `html_sidebars = {'**': ['']}`.


Configuration error:
Values in 'html_sidebars' must be a list of strings. At least one pattern has a string value: '**'. Change to `html_sidebars = {'**': ['']}`.