Resolve language-rule issues

[WilcoFiers]

This PR resolves a number of smaller language rule issues.

• Closes Should ACT rules allow fictional and/or extinct languages as a valid language? #1614 (comment)
• Clarify that body tag is optional, which is why some of the examples are applicable even without a body [off6ek]
• ...

Need for Call for Review: 1 week

---

How to Review And Approve

• Go to the “Files changed” tab
• Here you will have the option to leave comments on different lines.
• Once the review is completed, find the “Review changes” button in the top right, select “Approve” (if you are really confident in the rule) or "Request changes" and click “Submit review”.
• Make sure to also review the proposed Call for Review period. In case of disagreement, the longer period wins.

[netlify]

✅ Deploy Preview for act-rules ready!

Name	Link
🔨 Latest commit	605bbca
🔍 Latest deploy log	https://app.netlify.com/projects/act-rules/deploys/68fa424320604200080f3538
😎 Deploy Preview	https://deploy-preview-2365--act-rules.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.