docs: fix broken API reference link in README

[huanshenyi]

Description

Fix broken API Reference link in README.md that was returning 404 error.

The API Reference link was pointing to a non-existent local file (.sop/summary/interfaces.md). Updated to point to the correct
online documentation URL: https://strandsagents.com/latest/documentation/docs/api-reference/typescript/

Related Issues

Fixes #312

Documentation PR

N/A - This is a documentation fix in this repository

Type of Change

Documentation update

Testing

How have you tested the change?

• I ran npm run check
• Manually verified the new link works and points to correct API documentation

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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your choice.

[zastrowm]

Thank you!