Merge pull request #905 from stan-dev/reduce_sum_static_missing

Add missing index entry for reduce_sum_static

Author: WardBrian

src/functions-reference/higher-order_functions.qmd

@@ -675,6 +675,9 @@ parallelization of the resultant sum.
 \index{{\tt \bfseries reduce\_sum }!{\tt (F f, array[] T x, int grainsize, T1 s1, T2 s2, ...): real}|hyperpage}
 
 `real` **`reduce_sum`**`(F f, array[] T x, int grainsize, T1 s1, T2 s2, ...)`<br>\newline
+
+<!-- real; reduce_sum_static; (F f, array[] T x, int grainsize, T1 s1, T2 s2, ...); -->
+\index{{\tt \bfseries reduce\_sum\_static }!{\tt (F f, array[] T x, int grainsize, T1 s1, T2 s2, ...): real}|hyperpage}
 `real` **`reduce_sum_static`**`(F f, array[] T x, int grainsize, T1 s1, T2 s2, ...)`<br>\newline
 
 Returns the equivalent of `f(x, 1, size(x), s1, s2, ...)`, but computes