[doc] add Redis Sentinel and Apache Kvrocks monitoring help documentation

[SatyamPandey-07]

What's changed?

• Added user help documentation for Redis Sentinel monitoring in both English (home/docs/help/redis_sentinel.md) and Chinese (home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/redis_sentinel.md), detailing configuration parameters, SSH tunnel parameters, and metrics sets (server, clients, stats, cpu, sentinel).
• Added user help documentation for Apache Kvrocks monitoring in both English (home/docs/help/kvrocks.md) and Chinese (home/i18n/zh-cn/docusaurus-plugin-content-docs/current/help/kvrocks.md), detailing configuration parameters and metrics sets (server, clients, memory, persistence, stats, replication, cpu, cluster, commandstats, keyspace).
• Updated home/sidebars.json under the cache category to register help/redis_sentinel and help/kvrocks, eliminating 404 links from the monitoring console help buttons.

Checklist

• I have read the Contributing Guide
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

Add or update API

• I have added the necessary e2e tests and all cases have passed.

fixes #4370