Remove duplicated header snippet from redis.md

Removed duplicated header snippet from Redis documentation.

Author: gaobingyi

docs/database/redis.md

@@ -24,8 +24,6 @@ head:
 - [Redis 内存碎片详解](https://javaguide.cn/database/redis/redis-memory-fragmentation.html)
 - [Redis 常见阻塞原因总结](https://javaguide.cn/database/redis/redis-common-blocking-problems-summary.html)
 
-<!-- @include: @small-advertisement.snippet.md -->
-
 ## Redis 基础
 
 ### 什么是 Redis？