feat(i18n): enhance multilingual documentation and project structure

- Added new documentation files for MultiPost in Spanish, French, Indonesian, Japanese, Korean, and Russian.
- Updated existing documentation to include new language support and improved project structure.
- Removed outdated internationalization.mdc file and integrated relevant content into general.mdc.
- Enhanced layout components to accommodate the new multilingual features.

Author: harryisfish

.cursor/rules/general.mdc

@@ -5,6 +5,9 @@ alwaysApply: true
 ---
 This project is a Fumadocs.
 
+## Writing
+中文使用全角符号
+
 ## i18n
 When user want to create a new article, you should try to write the first article in English as a default. 
 Only when user require to finish the i18n, Then you should complete all other language.

.cursor/rules/internationalization.mdc

@@ -27,8 +27,9 @@ MultiPost-Blog/
 │   └── layout.tsx
 ├── content/
 │   └── docs/
-│       ├── introducing-multipost.mdx
-│       └── introducing-multipost.zh.mdx
+│       └── introducing-multipost/
+│           ├── index.mdx
+│           └── index.zh-Hans.mdx
 ├── lib/
 │   ├── i18n.ts
 │   └── source.ts