JS Conditions and Booleans: add demo

[PReichetanz]

Further Improvement Idea Before Review

• Render the goal for this demo in HTML like @ahohnsen in this example

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js-conditions-and-booleans/demo-start

📄 Rendered Exercise

🔎 Review

Review via 🔗 CodeSandbox or locally by running this command in your Terminal:

npx ghcd@latest neuefische/web-exercises/tree/js-conditions-and-booleans_demo/sessions/js-conditions-and-booleans/demo-start -i

✨ Copyable Markdown for Curriculum

Use this demo on
[🔗 **CodeSandbox**](https://codesandbox.io/s/github/neuefische/web-exercises/tree/main/sessions/js-conditions-and-booleans/demo-start?file=/README.md)
or locally by running this command in your Terminal:

npx ghcd@latest neuefische/web-exercises/tree/main/sessions/js-conditions-and-booleans/demo-start -i

js-conditions-and-booleans/demo-end

📄 Rendered Exercise

🔎 Review

Review via 🔗 CodeSandbox or locally by running this command in your Terminal:

npx ghcd@latest neuefische/web-exercises/tree/js-conditions-and-booleans_demo/sessions/js-conditions-and-booleans/demo-end -i

✨ Copyable Markdown for Curriculum

You can check out the final version of this demo on
[🔗 **CodeSandbox**](https://codesandbox.io/s/github/neuefische/web-exercises/tree/main/sessions/js-conditions-and-booleans/demo-end?file=/README.md)
or locally by running this command in your Terminal:

npx ghcd@latest neuefische/web-exercises/tree/main/sessions/js-conditions-and-booleans/demo-end -i