auto update README.md

Author: chech2

README.md

@@ -372,6 +372,7 @@
 |1476. 날짜 계산|[링크](./%EB%B0%B1%EC%A4%80/Silver/1476.%E2%80%85%EB%82%A0%EC%A7%9C%E2%80%85%EA%B3%84%EC%82%B0/README.md)|
 |14888. 연산자 끼워넣기|[링크](./%EB%B0%B1%EC%A4%80/Silver/14888.%E2%80%85%EC%97%B0%EC%82%B0%EC%9E%90%E2%80%85%EB%81%BC%EC%9B%8C%EB%84%A3%EA%B8%B0/README.md)|
 |14889. 스타트와 링크|[링크](./%EB%B0%B1%EC%A4%80/Silver/14889.%E2%80%85%EC%8A%A4%ED%83%80%ED%8A%B8%EC%99%80%E2%80%85%EB%A7%81%ED%81%AC/README.md)|
+|1515. 수 이어 쓰기|[링크](./%EB%B0%B1%EC%A4%80/Silver/1515.%E2%80%85%EC%88%98%E2%80%85%EC%9D%B4%EC%96%B4%E2%80%85%EC%93%B0%EA%B8%B0/README.md)|
 |1541. 잃어버린 괄호|[링크](./%EB%B0%B1%EC%A4%80/Silver/1541.%E2%80%85%EC%9E%83%EC%96%B4%EB%B2%84%EB%A6%B0%E2%80%85%EA%B4%84%ED%98%B8/README.md)|
 |15649. N과 M （1）|[링크](./%EB%B0%B1%EC%A4%80/Silver/15649.%E2%80%85N%EA%B3%BC%E2%80%85M%E2%80%85%EF%BC%881%EF%BC%89/README.md)|
 |15650. N과 M （2）|[링크](./%EB%B0%B1%EC%A4%80/Silver/15650.%E2%80%85N%EA%B3%BC%E2%80%85M%E2%80%85%EF%BC%882%EF%BC%89/README.md)|