Updating getting_started link in README.md

[Allentro]

Change from getting_started to installation inline with #687

Proposed changes

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Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Black formatted
• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

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[RemDelaporteMathurin]

Hey @Allentro welcome! Thanks for this fix, I forgot to change this link! 🎉

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ff6daff) 98.94% compared to head (25fc44b) 98.94%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #696   +/-   ##
=======================================
  Coverage   98.94%   98.94%           
=======================================
  Files          58       58           
  Lines        2188     2188           
=======================================
  Hits         2165     2165           
  Misses         23       23           

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