Bump Readme

[kellertuer]

This PR is just a bit of nice small changes

• add the new paper to the readme
• restructure the badges the same way they are organised in Manifolds.jl
• add a section that quotes both BibLaTeX citations

And this also fixes a small error we had in the docs, since one extref was broken, when the DefaultMetric moved from Manifolds.jl to ManifoldsBase.jl

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (8e6d17f) to head (31a29a1).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #89   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
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  Files           36        36           
  Lines         2899      2899           
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  Hits          2899      2899           

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[kellertuer]

Thanks for the help :)