[Task] Add user help documentation for Redis Sentinel and Apache Kvrocks monitoring

Description

In HertzBeat, both Redis Sentinel (app-redis_sentinel.yml) and Apache Kvrocks (app-kvrocks.yml) are fully supported monitoring templates under the cache category with designated helpLink URLs:

• https://hertzbeat.apache.org/docs/help/redis_sentinel
• https://hertzbeat.apache.org/docs/help/kvrocks

However, the corresponding user help documents in home/docs/help/ (English) and home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/ (Chinese) are currently missing, and they are not included in home/sidebars.json. When users click the "Help" button from the HertzBeat console, it leads to 404 pages.

Task List

• Add English help doc for Redis Sentinel (home/docs/help/redis_sentinel.md)
• Add Chinese help doc for Redis Sentinel (home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/redis_sentinel.md)
• Add English help doc for Apache Kvrocks (home/docs/help/kvrocks.md)
• Add Chinese help doc for Apache Kvrocks (home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/kvrocks.md)
• Register both docs in home/sidebars.json under the cache category