Fix incorrect path to notebooks/ in docs/README_CN and docs/README_JP

[takeru1205]

Pull Request Title

Description

Purpose of the PR

• notebooks/ directory in the docs/README_CN.md and docs/README_JP.md files. The existing paths were written as ./notebooks but should be ../notebooks.

Related Issue(s)

• N/A

Changes

• Corrected the notebook directory reference from ./notebooks to ../notebooks in docs/README_CN.md.
• Corrected the notebook directory reference from ./notebooks to ../notebooks in docs/README_JP.md.

Model/Algorithm Performance

• N/A (This PR does not involve changes to models or algorithms.)

Dependencies

• No new dependencies were introduced.

Reviewer Notes

• Please review the changed paths in both README files to confirm that they now correctly point to the notebooks/ directory.

Confirmed

• I have updated the documentation accordingly.
• I have adhered to the coding standards and guidelines of this project.
• I have added comments, especially in hard-to-understand areas.