docs: mark-cell,mark-chord

[Orcish-Y]

update docs。
mark :cell,chord

[petercat-assistant]

Walkthrough

This pull request updates the documentation for the mark-cell and mark-chord components in the G2 library. It introduces new sections and examples to better illustrate the usage and configuration of these components, enhancing clarity and usability for developers.

Changes

File	Summary
site/docs/manual/core/mark/cell.zh.md, site/docs/manual/core/mark/chord.zh.md	Updated documentation with new sections, examples, and configuration details for mark-cell and mark-chord.

[coveralls]

Pull Request Test Coverage Report for Build 13779754336

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.69%

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Totals
Change from base Build 13769369610:	0.0%
Covered Lines:	10617
Relevant Lines:	11872

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💛 - Coveralls