update methodology vignettes

[sbfnk]

Description

This PR closes #916.

Initial submission checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have tested my changes locally (using devtools::test() and devtools::check()).
• I have added or updated unit tests where necessary.
• I have updated the documentation if required and rebuilt docs if yes (using devtools::document()).
• I have followed the established coding standards (and checked using lintr::lint_package()).
• I have added a news item linked to this PR.

After the initial Pull Request

• I have reviewed Checks for this PR and addressed any issues as far as I am able.

[sbfnk]

To be picked up again once proposed model changes in other PRs have been finalised.

[github-actions]

Thank you for your contribution sbfnk 🚀! Your synthetic_recovery markdown is ready for download 👉 here 👈!
_{(The artifact expires on 2025-02-04T14:11:48Z. You can re-generate it by re-running the workflow here.)}