docs: add metadata and header tag info

[zmzlois]

Summary

• add metadata and header tag backlink from custom-page section

Related Issue

N/A

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Timeless0911]

Thanks a lot! Are you familiar with Chinese? Can you help translate the docs of Chinese version?

[chenjiahan]

@zmzlois can you check the above comments