Add tutorial for fanout pipeline

[qbc2016]

AgentScope Version

[The version of AgentScope you are working on, e.g. import agentscope; print(agentscope.__version__)]

Description

• Add tutorial for fanout pipeline
• Fix some docstring format

Checklist

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

• Code has been formatted with pre-commit run --all-files command
• All tests are passing
• Docstrings are in Google style
• Related documentation has been updated (e.g. links, examples, etc.)
• Code is ready for review

[Copilot]

Pull Request Overview

This PR adds a comprehensive tutorial for the fanout pipeline feature in AgentScope and improves docstring formatting across the codebase. The fanout pipeline allows distributing the same input to multiple agents and collecting their responses, complementing the existing sequential pipeline functionality.

• Adds documentation and examples for fanout_pipeline and FanoutPipeline in both English and Chinese tutorials
• Fixes docstring formatting in OpenAI and DashScope tool modules for better readability
• Updates documentation links to use proper reStructuredText format

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/agentscope/tool/_multi_modality/_openai_tools.py	Improves docstring formatting with proper bullet points and line breaks
src/agentscope/tool/_multi_modality/_dashscope_tools.py	Updates documentation link format and improves readability
docs/tutorial/zh_CN/src/task_pipeline.py	Adds Chinese tutorial content for fanout pipeline with examples and usage notes
docs/tutorial/en/src/task_pipeline.py	Adds English tutorial content for fanout pipeline with examples and usage notes

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[DavdGao]

LGTM