Article: https://wordpress.org/documentation/article/template-editor/

Update for 6.6

• Template editor/inspector: show and select related patterns 55091
• Template Parts: Update replace flow to separate template parts from patterns 60203
• Browse and try alternative templates in the sidebar, see Template inspector: Surface related patterns 55091
• Add a replace flow to the inspector controls 55128
• Add bulk actions toolbar 59714
• Add actions to list layout 60805
• Update index page for templates 59792
• Index view for Templates & Parts: Use grid layout as default 60069
• Simplify template reset language 60256

General

• Make sure all screenshots are relevant to the latest version
• Make sure videos, if any, are up to date
• Add ALT tags for the images
• Make sure the headings are in sentence case
• Convert all reusable blocks to a ‘regular block’.
• Update the changelog at the end of the article

Notes

1. We are not adding detailed updates for the Block settings - Typography, Color, Layout, Dimension and Border and for the More Options setting in the block toolbar. Pls mention the settings included for the block and link to the detailed settings pages instead.
2. Some of the PRs have great videos that can be added to the article.