[qty.expr.temp.algo] Avoid possible ambiguity of "constant"

docs/api_reference/src/quantities.tex

@@ -957,7 +957,7 @@
 \item
 If $y = 1$, returns \tcode{OneType\{\}}.
 \item
-Otherwise, if the result is a constant, returns $y$.
+Otherwise, if the result is a single constant, returns $y$.
 \item
 Otherwise, returns \tcode{To<$y$>}
 after applying the following mappings and