add version tag badge

[taozhiyu]

Hi there! I wanted to share that I've noticed YOURLS/YOURLS.pot#41 has released a new dev version. I've proactively updated the translation files to align with the latest release.

To improve project visibility and user experience, may I suggest adding a version compatibility badge to the repository? This could be implemented using Shields.io or similar service to dynamically display the supported YOURLS version. Such a badge would:

1. Provide immediate version awareness for visitors
2. Reduce maintenance overhead by automating version tracking
3. Increase transparency for potential contributors

I originally planned to add versioning to each translation repository, but I found that they don’t use tags or releases effectively. Adding a badge would make it easier for others who are willing to update the translations.

The badge could follow this format:

https://img.shields.io/github/v/release/USER/REPO?include_prereleases&display_name=release&style=flat-square&logo=github

↑↑ See that? It's very clear.

[LeoColomb]

Thanks for submitting this pull request, @taozhiyu.
While the goal is clear and great, I'm afraid of the maintenance cost this will cost.
Very few translation repos are actually tagging releases, which breaks version automation of the badge.
Again, the idea is great, but I'm not sure the implementation is great in the long term.
@YOURLS/core?

[toineenzo]

I think this would be a very good idea. I also just created a poll here to start gathering translations in 1 official repo to make it much easier to maintain translations: https://github.com/orgs/YOURLS/discussions/3872
be sure to vote :)