Update day15.md (#763)

Author: jportway

docs/2024/puzzles/day15.md

@@ -13,6 +13,7 @@ https://adventofcode.com/2024/day/15
 - [Solution](https://github.com/AlexMckey/AoC2024_Scala/blob/master/src/year2024/day15.scala) by [Alex Mc'key](https://github.com/AlexMckey)
 - [Solution](https://github.com/rmarbeck/advent2024/blob/main/day15/src/main/scala/Solution.scala) by [Raphaël Marbeck](https://github.com/rmarbeck)
 - [Solution](https://github.com/TheDrawingCoder-Gamer/adventofcode2024/blob/master/src/main/scala/Day15.scala) by [Bulby](https://github.com/TheDrawingCoder-Gamer)
+- [Solution](https://github.com/jportway/advent2024/blob/master/src/main/scala/Day15.scala) by [Joshua Portway](https://github.com/jportway)
 
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