added link for count_if.md

Author: rotarymars

reference/algorithm/count_if.md

@@ -54,6 +54,12 @@ int main() {
 }
 ```
 * std::count_if[color ff0000]
+* std::vector[link /reference/vector/vector.md]
+* std::count_if[link /reference/algorithm/count_if.md]
+* v.begin[link /reference/vector/vector/begin.md]
+* v.end[link /reference/vector/vector/end.md]
+* std::cout[link /reference/iostream/cout.md]
+* std::endl[link /reference/ostream/endl.md]
 
 ### 出力
 ```cpp