chore: Improved km localization

[huypanha]

Description

This update only translates untranslated words and improves the translation to make it easier to understand.

Type of Change

• [ ] ✨ Feature: New functionality without breaking existing features.
• [ ] 🛠️ Bug fix: Resolves an issue without altering current behavior.
• [ ] 🧹 Refactor: Code reorganization, no behavior change.
• [ ] ❌ Breaking: Alters existing functionality and requires updates.
• [ ] 🧪 Tests: New or modified tests
• [ ] 📝 Documentation: Updates or additions to documentation.
• [x] 🗑️ Chore: Routine tasks, or maintenance.
• [ ] ✅ Build configuration change: Build/configuration changes.

[EchoEllet]

Can you update CHANGELOG.md?

## [Unreleased]

+ ### Changed
+
+ - Improve khmer localization [#2372](https://github.com/singerdmx/flutter-quill/pull/2372).

## [11.0.0-dev.12] - 2024-11-11

[EchoEllet]

Thanks.