fix(theme): only parse HTML- and JSX-style comments in MD code

[Josh-Cena]

Motivation

Fix #7032

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

[netlify]

✅ [V2]

Name	Link
🔨 Latest commit	68e6018
🔍 Latest deploy log	https://app.netlify.com/sites/docusaurus-2/deploys/62410f5ee0d441000922de08
😎 Deploy Preview	https://deploy-preview-7033--docusaurus-2.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 site settings.

[github-actions]

⚡️ Lighthouse report for the changes in this PR:

Category	Score
🔴 Performance	49
🟢 Accessibility	100
🟢 Best practices	92
🟢 SEO	100
🟢 PWA	90

Lighthouse ran on https://deploy-preview-7033--docusaurus-2.netlify.app/

[github-actions]

Size Change: +49 B (0%)

Total Size: 807 kB

Filename	Size	Change
website/build/assets/js/main.********.js	613 kB	+49 B (0%)

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/globalData.json	49.9 kB
website/build/assets/css/styles.********.css	105 kB
website/build/index.html	38.4 kB

_{compressed-size-action}