[Doc] Improve the doc for sink

[banmoy]

What type of PR is this：

• [ ] BugFix
• [ ] Feature
• [ ] Enhancement
• [ ] Refactor
• [ ] UT
• [X] Doc
• [ ] Tool

Which issues of this PR fixes ：

Fixes #

Problem Summary(Required) ：

• consolidate the structure of the doc
• make examples clear
• correct parameter description
• add best practices

Checklist:

• [ ] I have added test cases for my bug fix or my new feature
• [ ] This pr will affect users' behaviors
• [ ] This pr needs user documentation (for new or modified features or behaviors)
• [ ] I have added documentation for my new feature or new function