Documentation provided
I supplied usage documentation to this usertag template. In addition to recoloring it, I also supplied it something important that was missing: a fallback behavior that was necessary whenever the then-mandatory argument (the username) was not supplied (either by using {{User Wikipedia}} with no arguments or {{User Wikipedia|}} with a blank or null argument).
Now that the page looks complete, it would be a good idea to protect it from vandalism (just like the Twitter and YouTube Account usertags). If you don’t like the recoloring, then feel free to change it. ----SilSinn (Pokémon Sun TID: 768426; Pokémon Ultra Moon TID: 123446) (talk) 05:23, 26 November 2018 (UTC)