Merge pull request #197 from th-ch/skasch/add-leaderboard-readme

Add link to the leaderboard in README.md

README.md

@@ -12,6 +12,11 @@ These are proposed solutions for the [Advent of Code 2023](http://adventofcode.c
 
 The solutions are automatically tested with github-actions.
 
+An automatically updated
+[leaderboard](https://cs-advent-of-code-2023.netlify.app/) summarizes the
+execution times of each entry submitted for each problem. It takes a few
+minutes to update once a new submission is merged.
+
 [![Build Status](https://github.com/th-ch/adventofcode-2023/workflows/CI/badge.svg)](https://github.com/th-ch/adventofcode-2023/actions?query=branch%3Amain)
 
 - [Usage](#usage)