Improve repository cosmetics

Love the long Readme 👏

Suggestions for cosmetic improvements:
- [ ] Add short description on top of Repo site (not in Readme)
- [ ] Reference the FIN4Xplorer repos or the www.finfour.net side somewhere?
- [ ] Readme: Name on top should be FIN4Simulations not FIN4Sim
- [ ] Readme: Headings should be formatted in GitHub Markdown: `#`, `##`, `###`, `####`
- [ ] Readme: better formatting of links using the `[ link name ] ( URL )` syntax, like [python 3](https://www.python.org/download/releases/3.0/)
- [ ] Readme: better formatting of code snippets using the \` syntax \`, like `pip3 install cadCAD`

Review the repository description and README against each checklist item, including the requested naming, headings, links, and code formatting. Done means the repository description and all listed README references and formatting improvements are addressed.

Written by the indexing model from the issue text.