[Fix][Doc] Sink's plugin_input is incorrect configurations

[e-mhui]

@Hisoka-X Hello, pls help to review it.

Sink's plugin_input is incorrect configurations,it should be same with Source's plugin_output. (The English document is correct, but the Chinese document is incorrect.)

Although it does not affect task execution, this is an incorrect method and is not recommended. Placing it in the official documentation can cause confusion.

seatunnel/seatunnel-engine/seatunnel-engine-core/src/main/java/org/apache/seatunnel/engine/core/parse/ConfigParserUtil.java

Line 112 in 9777ecb

// Compatible with previous issues

Purpose of this pull request

Does this PR introduce any user-facing change?

How was this patch tested?

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config

[Hisoka-X]

Thanks @e-mhui