fix: improve docs and example (#2508)

## AgentScope-Java Version

[The version of AgentScope-Java you are working on, e.g. 1.0.12, check
your pom.xml dependency version or run `mvn dependency:tree | grep
agentscope-parent:pom`(only mac/linux)]

## Description

[Please describe the background, purpose, changes made, and how to test
this PR]

## Checklist

Please check the following items before code is ready to be reviewed.

- [ ]  Code has been formatted with `mvn spotless:apply`
- [ ]  All tests are passing (`mvn test`)
- [ ]  Javadoc comments are complete and follow project conventions
- [ ] Related documentation has been updated (e.g. links, examples,
etc.)
- [ ]  Code is ready for review