Add version badge in navbar for better visibility

Description

Currently, the website does not clearly show which version of Kmesh documentation is being viewed. This can create confusion for users, especially when updates or multiple versions exist.

Proposed Solution
Add a small version badge (e.g., v1.1.0) in the top navbar
Place it near the search bar or right-side icons
Fetch version dynamically (e.g., from config or package.json)
Expected Outcome
Clear visibility of current version
Improved user experience and clarity