添加按类别创建促销

Change-Id: If9a0d78bfd14030782c24a0fa07b66cddea69d1e
diff --git a/src/main/java/com/example/myproject/service/PromotionService.java b/src/main/java/com/example/myproject/service/PromotionService.java
index b83bce5..2122411 100644
--- a/src/main/java/com/example/myproject/service/PromotionService.java
+++ b/src/main/java/com/example/myproject/service/PromotionService.java
@@ -18,4 +18,5 @@
     double getDownloadDiscount(Long torrentId);
 
 
-} 
\ No newline at end of file
+
+}
\ No newline at end of file