Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -186,6 +186,7 @@ _**Note:** Our group is currently taking a break from grinding leetcode. The tab
 | December 20, 2024 | [2415](https://leetcode.com/problems/reverse-odd-levels-of-binary-tree/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2415) | 🟡 Medium |
 | December 21, 2024 | [2872](https://leetcode.com/problems/maximum-number-of-k-divisible-components/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2872) | 🔴 Hard |
 | December 22, 2024 | [2940](https://leetcode.com/problems/find-building-where-alice-and-bob-can-meet/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2940) | 🔴 Hard |
+| December 23, 2024 | [2471](https://leetcode.com/problems/minimum-number-of-operations-to-sort-a-binary-tree-by-level/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2471) | 🟡 Medium |
 
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