fix: modified language tag (doocs#680)

YangFong · web-flow · commit 2d9a5a9214cc · 2022-01-22T08:21:53.000+08:00
diff --git a/solution/0400-0499/0415.Add Strings/README.md b/solution/0400-0499/0415.Add Strings/README.md
@@ -63,9 +63,9 @@ class Solution {
 }
 ```
 
-### **TypeScript**
+### **JavaScript**
 
-```ts
+```js
 /**
  * @param {string} num1
  * @param {string} num2
diff --git a/solution/0400-0499/0415.Add Strings/README_EN.md b/solution/0400-0499/0415.Add Strings/README_EN.md
@@ -78,9 +78,9 @@ class Solution {
 }
 ```
 
-### **TypeScript**
+### **JavaScript**
 
-```ts
+```js
 /**
  * @param {string} num1
  * @param {string} num2
diff --git a/solution/0400-0499/0415.Add Strings/Solution.js b/solution/0400-0499/0415.Add Strings/Solution.js
