refactor: onMounted code highlighted

[proghasan]

Description of Problem

onMounted use in single code. it is not highlight

Proposed Solution

I used markdown syntax instead single code.

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
docs-bn	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 17, 2024 2:47pm

[netlify[bot]]

✅ Deploy Preview for docs-bn ready!

Name	Link
🔨 Latest commit	b3f71b17fbb55983164bc28b3d50730627e6b0c4
🔍 Latest deploy log	https://app.netlify.com/sites/docs-bn/deploys/65a7e84c28f1eb00073a3018
😎 Deploy Preview	https://deploy-preview-61--docs-bn.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 configuration.

[mahmudunnabikajal]

@proghasan, appreciate your contribution! ❤️