If you go to https://www.wikitree.com/wiki/Fisher-29079 press the edit button, scroll down to the biography you will see the added text.
[[Category: 2nd Regiment, Michigan Infantry, United States Civil War]]
Here's the link to the US Civil War Project, there's hints there about categories and stickers. https://www.wikitree.com/wiki/Project:US_Civil_War:_War_Between_the_States