Enhance README: Shields to capture the attention of potential contributors

I noticed you have opened issues labeled help wanted. I recommend enhancing the README to make the call for new contributors more prominent.

Changes Made:

Shields: Added Shields.io badges at the top of the README

[![GitHub repo Good Issues for newbies](https://img.shields.io/github/issues/GFZ/arosics/good%20first%20issue?style=flat&logo=github&logoColor=green&label=Good%20First%20issues)](https://github.com/GFZ/arosics/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) [![GitHub Help Wanted issues](https://img.shields.io/github/issues/GFZ/arosics/help%20wanted?style=flat&logo=github&logoColor=b545d1&label=%22Help%20Wanted%22%20issues)](https://github.com/GFZ/arosics/issues?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22) [![GitHub Help Wanted PRs](https://img.shields.io/github/issues-pr/GFZ/arosics/help%20wanted?style=flat&logo=github&logoColor=b545d1&label=%22Help%20Wanted%22%20PRs)](https://github.com/GFZ/arosics/pulls?q=is%3Aopen+is%3Aissue+label%3A%22help+wanted%22) [![GitHub repo Issues](https://img.shields.io/github/issues/GFZ/arosics?style=flat&logo=github&logoColor=red&label=Issues)](https://github.com/GFZ/arosics/issues?q=is%3Aopen)

Welcoming Message: Enhanced the README with a more prominent and inviting message to welcome new contributors.

Why This Matters:

Attract New Contributors: Considering there is a number of opened issues labeled 'Help Wanted' - a welcoming and appealing README is one of the most efficient ways to attract new contributors

Additional Resources:

For more insights into building a strong open-source community, check out the Building Community guide.

🚀 Thank you for considering this pull request! 🚀

GFZ / arosics

Enhance README: Shields to capture the attention of potential contributors #51

Changes Made:

Why This Matters:

Additional Resources:

1. Dynamic Top Contributors (with avatars linked to contributor profiles)

2. Repo Stats