fix naming

snippets/sum-array-numbers.md

@@ -0,0 +1,8 @@
+### Sum of array of numbers
+
+Use `Array.reduce()` to add each value to an accumulator, initialized with a value of `0`.
+
+```js
+const sumArrayNumbers = arr => arr.reduce((acc, val) => acc + val, 0);
+// sum([1,2,3,4]) -> 10
+```