Release 3.0 checklist

[mpound]

Checklist for release 3.0

• CHANGES.md
• smc models added
• updated wk2020
• website fully updated with new model plots and descriptions
• notebooks updated and run without errors
• all relevant issues resolved
• ensure docs build
• push notebooks to pdrtpy-nb
• merge PR for new notebooks
• merge 3.0 release branch to main
• update README.rst for new notebooks
• release through github
• announce