Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -35,6 +35,7 @@ This means you'll always find an AI-generated solution to compare with or learn
 | November 13, 2025 | [3228](https://leetcode.com/problems/maximum-number-of-operations-to-move-ones-to-the-end/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3228) | 🟡 Medium |
 | November 14, 2025 | [2536](https://leetcode.com/problems/increment-submatrices-by-one/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2536) | 🟡 Medium |
 | November 15, 2025 | [3234](https://leetcode.com/problems/count-the-number-of-substrings-with-dominant-ones/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3234) | 🟡 Medium |
+| November 16, 2025 | [1513](https://leetcode.com/problems/number-of-substrings-with-only-1s/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/1513) | 🟡 Medium |
 
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