[algorithm.syn] Add missing comma

Author: cpplearner

source/algorithms.tex

@@ -2219,7 +2219,7 @@
     template<class I, class O>
       using @\libglobal{replace_copy_if_result}@ = in_out_result<I, O>;
 
-    template<@\libconcept{input_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class O, class T = iter_value_t<O>
+    template<@\libconcept{input_iterator}@ I, @\libconcept{sentinel_for}@<I> S, class O, class T = iter_value_t<O>,
              class Proj = identity, @\libconcept{indirect_unary_predicate}@<projected<I, Proj>> Pred>
       requires @\libconcept{indirectly_copyable}@<I, O> && @\libconcept{output_iterator}@<O, const T&>
       constexpr replace_copy_if_result<I, O>