Update day18.md (#753)

Add Day18 solution by Alex Mc'key

docs/2024/puzzles/day18.md

@@ -9,7 +9,8 @@ https://adventofcode.com/2024/day/18
 ## Solutions from the community
 - [Solution](https://github.com/nikiforo/aoc24/blob/main/src/main/scala/io/github/nikiforo/aoc24/D18T2.scala) by [Artem Nikiforov](https://github.com/nikiforo)
 - [Solution](https://github.com/spamegg1/aoc/blob/master/2024/18/18.worksheet.sc#L125) by [Spamegg](https://github.com/spamegg1/)
-- [Solution](https://github.com/rmarbeck/advent2024/blob/main/day18/src/main/scala/Solution.scala) by [Raphaël Marbeck](https://github.com/rmarbeck)  
+- [Solution](https://github.com/rmarbeck/advent2024/blob/main/day18/src/main/scala/Solution.scala) by [Raphaël Marbeck](https://github.com/rmarbeck)
+- [Solution](https://github.com/AlexMckey/AoC2024_Scala/blob/master/src/year2024/day18.scala) by [Alex Mc'key](https://github.com/AlexMckey)
 
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