Fix example operation code

[morganjcw]

This is a:

• [ x] bug fix PR with no breaking changes — please ensure the base branch is main
• [ ] new functionality — please ensure the base branch is the latest dev/ branch
• [ ] a breaking change — please ensure the base branch is the latest dev/ branch

Description & motivation

This is a minor fix to the docs for example code for generate_model_yaml. The existing example does not compile due to the square brackets around the sample model. Removing the brackets allows the operation to run.

Checklist

• [x ] I have verified that these changes work locally
• [ x] I have updated the README.md (if applicable)
• [x] I have added tests & descriptions to my models (and macros if applicable)
• [x] I have added an entry to CHANGELOG.md

[github-actions[bot]]

This PR has been marked as Stale because it has been open with no activity as of late. If you would like the PR to remain open, please comment on the PR or else it will be closed in 7 days.