docs: update RangePicker month demo

[zombieJ]

中文版模板 / Chinese template

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• TypeScript definition update
• Bundle size optimization
• Performance optimization
• Enhancement feature
• Internationalization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Workflow
• Other (about what?)

🔗 Related issue link

ref #48835 #48590

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	-
🇨🇳 Chinese	-

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

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[github-actions]

👁 Visual Regression Report for PR #48844 Failed ❌

🎯 Target branch: master (e2e3331)
📖 View Full Report ↗︎

Expected (Branch master)	Actual (Current PR)	Diff
date-picker-select-in-range.compact.png	date-picker-select-in-range.compact.png
date-picker-select-in-range.compact.png	date-picker-select-in-range.compact.css-var.png
date-picker-select-in-range.dark.png	date-picker-select-in-range.dark.png
date-picker-select-in-range.dark.png	date-picker-select-in-range.dark.css-var.png
date-picker-select-in-range.default.png	date-picker-select-in-range.default.png
date-picker-select-in-range.default.png	date-picker-select-in-range.default.css-var.png

Check Full Report for details

[github-actions]

[github-actions]

size-limit report 📦

Path	Size
./dist/antd.min.js	337.62 KB
./dist/antd-with-locales.min.js	385.5 KB

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (fec2132) to head (d301204).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master    #48844   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          746       746           
  Lines        12994     12994           
  Branches      3411      3411           
=========================================
  Hits         12994     12994           

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