Update README.md

Author: yanglbme

solution/0900-0999/0921.Minimum Add to Make Parentheses Valid/README.md

@@ -288,7 +288,7 @@ function minAddToMakeValid(s: string): number {
 
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-### Solution 3: Replace + recursion
+### 方法三：替换 + 递归
 
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