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
• [x] CHANGELOG.md updated
• [x] Documentation updated (if needed).

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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

Additional details and impacted files

```diff @@ 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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