See: https://www.wikitree.com/wiki/Category:Browns_Hill_Burying_Ground%2C_Orient%2C_New_York. The proper category will be: [[Category:Browns Hill Burying Ground, Orient, New York]]
The technique I use to find cemetery categories on WikiTree is to Google WikiTree County-Name State-Name Cemeteries. If the cemetery is already on WikiTree, this should take you either:
1. Directly to the list of cemeteries in the county.
2. To a category containing another cemetery within that county and state.
In case 2, click on the link and then click on the county name on the ensuing screen.