[Doc][Iceberg] Improved iceberg documentation

[Carl-Zhou-CN]

subtask of #4572

Purpose of this pull request

Check list

• Code changed are covered with tests, or it does not need tests for reason:
• 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 change log that in connector document. For more details you can refer to connector-v2
  2. Update plugin-mapping.properties and add new connector information in it
  3. Update the pom file of seatunnel-dist
• Update the release-note.

[zhilinli123]

https://github.com/apache/seatunnel/blob/dev/docs/en/connector-v2/source/Mysql.md

Refer to the current documentation to add a jar dependent address boot for the user

[Carl-Zhou-CN]

done

[zhilinli123]

good , Thanks for your contribution. Looks good PTAL : @hailin0

[zengqinchris]

When can use the function of sink to iceberg