Add card generation website

**Is your feature request related to a problem? Please describe.**

I think it would be nice to have a card creation website for this project. This would allow users to generate the markdown code for our card using a simple interface. @anuraghazra, I vaguely remember you already did some work on this. No pressure, I just created this issue so we can track this feature.

**Example**

I think something like https://github-readme-streak-stats.herokuapp.com/demo would be amazing! Unfortunately, this example is coded in PHP. For future maintainability, I however think using a framework like React with https://mui.com is the better choice (see https://github.com/DenverCoder1/github-readme-streak-stats/tree/main/src/demo).