add concepts for (modelling) uncertainties

[LillyG901]

Summary of the discussion

See issue #1829

Type of change (CHANGELOG.md)

Add

• Added classes, instances and relations needed to model uncertainties

Workflow checklist

Automation

Closes #1829

PR-Assignee

• [ ] 🐙 Follow the Pull Request Workflow
• [x] 📝 Update the CHANGELOG.md
• [x] 📙 Add #'s to term tracker annotation

Reviewer

• [ ] 🐙 Follow the Reviewer Guide
• [ ] 🐙 Provided feedback and show sufficient appreciation for the work done