[doc] translate help document for memcached monitoring

[LiuTianyou]

What's changed?

1. translate help document for memcached monitoring
2. delete repeat content in pulsar.md

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.