docs mark density

[Orcish-Y]

docs: mark density

[petercat-assistant]

Walkthrough: This pull request updates the documentation for the cell and density mark types in the G2 library. It introduces new sections and examples to illustrate the usage of these marks, focusing on their configuration options and visual encoding capabilities.

Changes:

File	Summary
site/docs/manual/core/mark/cell.zh.md	Added detailed documentation for the cell mark, including configuration options, visual encoding, and examples.
site/docs/manual/core/mark/density.zh.md	Enhanced the density mark documentation with new examples and detailed descriptions of configuration options.

[coveralls]

Pull Request Test Coverage Report for Build 13802436038

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

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 13801596943:	0.0%
Covered Lines:	10617
Relevant Lines:	11872

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 13788634771

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%

---

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

---

💛 - Coveralls