request: Document C-optimal option in notebook

[rolandriver]

Contributor License Agreement

• A Contributor License Agreement signature is requested for any first PR contribution. Further information can be found in our contributing guidelines.

Motivation

Since there is a new implementation using C-Optimal for error budgeting, this feature should be documented in the corresponding notebook.

Proposed solution

Add a section about C-Optimal method in the error budget notebook.

Potential alternatives

No response

Additional context

No response