Small wording fix for empty_view

Author: ednolan

paper/P2728.md

@@ -5413,7 +5413,7 @@ with that object. Let `E` be an expression and let `T` be
 `@*utf-range*@`, `to_utfN(E)` is ill-formed. The expression `to_utfN(E)` is
 expression-equivalent to:
 
-- If `Char` is a specialization of `empty_view` ([range.empty.view]), then
+- If `V` is a specialization of `empty_view` ([range.empty.view]), then
   `empty_view<Char>{}`.
 
 - Otherwise, if `T` is an array type of known bound, then: