Quarto FollowUp

[epinzur]

Make Ben's requested changes from PR https://github.com/kaskada-ai/kaskada/pull/799

[epinzur]

• [x] Consider improving the CI flow
• [x] Add an _extensions README.md
• [x] Move Slack-Join URL to a variable (not possible)
• [ ] Attempt to move index text to separate files
• [x] Add a _scripts README.md
• [x] Re-add comments to the bluesky example
• [x] Convert the reddit example to qmd
• [ ] Adjust spacing of docstrings for aliases
• [ ] Create Issue/PR to on include-code-files extension to support start & end tags
• [ ] Add a comment to the commented-out fields
• [ ] Refactor the card template to not require design-styles.css
• [ ] Move announcement text to a variable