fix: Versions in docs (fix #1532)

[yash-dayama]

Title: fix: Versions in docs (fix #1532)

Description:

This PR adds version information to the Vue Router documentation to help users understand which version of the documentation is available in their preferred language. This addresses issue #1532 where users had no way of knowing if their language's documentation was up to date with the latest features.

Changes made:
- Updated config.js to include version information in language labels
- Added version tracking fields for each language
- Added version information tips to each language's README.md:
  - English (Up to v2.6)
  - French (Up to v2.5)
  - Japanese (Up to v2.4)
  - Chinese (Up to v2.3)
  - Russian (Up to v2.1)
  - Korean (Up to v2.0)

This helps users by:
- Clearly showing which version each translation covers
- Making it easy to see if a specific feature is documented in their language
- Helping users decide whether to use English docs for newer features

Implementation:
- Added version information to language selector in the navigation
- Added prominent version notices at the top of each language's main documentation
- Maintained consistent formatting across all languages
- Preserved all existing documentation content and structure

Testing:
- Verified version information appears correctly in language selector
- Confirmed version tips display properly in all language versions
- Checked formatting and layout consistency across all pages

This implements the solution proposed in the original issue while maintaining the documentation's clean and professional appearance.

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