Update README.md

Author: obalunenko

README.md

@@ -24,7 +24,7 @@ This repository contains solutions for puzzles and cli tool to run solutions to
 <details>
   <summary>2015</summary>  
 
-  - [ ] [Day 1: Not Quite Lisp](https://adventofcode.com/2015/day/1)
+  - [x] [Day 1: Not Quite Lisp](https://adventofcode.com/2015/day/1)
   - [ ] [Day 2: I Was Told There Would Be No Math](https://adventofcode.com/2015/day/2)
   - [ ] [Day 3: Perfectly Spherical Houses in a Vacuum](https://adventofcode.com/2015/day/3)
   - [ ] [Day 4: The Ideal Stocking Stuffer](https://adventofcode.com/2015/day/4)