Add info on citing FROG to README.md

[alexdewar]

Description

Now that we have a release published on Zenodo 🥳, we should give instructions on how to cite the code. Add instructions to the readme as well as a badge for the DOI corresponding to the latest version.

Closes #974.

Type of change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Documentation (non-breaking change that adds or improves the documentation)
• Optimisation (non-breaking, back-end change that speeds up the code)

Key checklist

• Pre-commit hooks run successfully (pre-commit run -a)
• All tests pass (pytest)
• The documentation builds without warnings (mkdocs build -s)
• Check the GUI still works (if relevant)
• Check the code works with actual hardware (if relevant)
• Check the pyinstaller-built executable works (if relevant)

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests have been added or an issue has been opened to tackle that in the future. (Indicate issue here: # (issue))

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.76%. Comparing base (d9bc90f) to head (0ce8c3e).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #975   +/-   ##
=======================================
  Coverage   86.76%   86.76%           
=======================================
  Files          69       69           
  Lines        3694     3694           
=======================================
  Hits         3205     3205           
  Misses        489      489           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull request overview

This PR updates the repository’s top-level documentation to include citation guidance now that FROG has a Zenodo release/DOI, making it easier for researchers to properly reference the software.

Changes:

• Add a Zenodo DOI badge alongside existing project status badges.
• Add a “Citing this software” section linking to Zenodo for citation details.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[dc2917]

Nice!