add js solution to readme documents for leetcode problem: no.0001

Author: tchx626

solution/0000-0099/0001.Two Sum/README.md

@@ -93,6 +93,21 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+var twoSum = function (nums, target) {
+  const map = new Map();
+  for (let i = 0; i < nums.length; i++) {
+    if (map.has(target - nums[i])) {
+      return [map.get(target - nums[i]), i];
+    }
+    map.set(nums[i], i);
+  }
+  return [];
+};
+```
+
 ### **...**
 
 ```

solution/0000-0099/0001.Two Sum/README_EN.md

@@ -79,6 +79,21 @@ class Solution {
 }
 ```
 
+### **JavaScript**
+
+```js
+var twoSum = function (nums, target) {
+  const map = new Map();
+  for (let i = 0; i < nums.length; i++) {
+    if (map.has(target - nums[i])) {
+      return [map.get(target - nums[i]), i];
+    }
+    map.set(nums[i], i);
+  }
+  return [];
+};
+```
+
 ### **...**
 
 ```

solution/0000-0099/0001.Two Sum/Solution.js

@@ -40,4 +40,5 @@ var twoSum = function (nums, target) {
     }
     map.set(nums[i], i);
   }
+  return [];
 };