Feature/issue 210 add gif to readme

[danielfromearth]

GitHub Issue: #210

Description

This change adds a gif — showing basic usage — to the README.

PR Acceptance Checklist

• [n/a] Unit tests added/updated and passing.
• [n/a] Integration testing
• CHANGELOG.md updated
• Documentation updated (if needed).

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📚 Documentation preview 📚: https://ncompare--211.org.readthedocs.build/en/211/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.95%. Comparing base (3d8e2f8) to head (e1c7a1c).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #211   +/-   ##
========================================
  Coverage    89.95%   89.95%           
========================================
  Files            5        5           
  Lines          468      468           
========================================
  Hits           421      421           
  Misses          47       47           

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