fix: remove doubled word in ethereum-for-web2-auth tutorial

[Oreemo]

Description

Fixed a typo in the "Using Ethereum for web2 authentication" tutorial where "a a" appeared instead of "a" on line 40.

Changes:

• File: public/content/developers/tutorials/ethereum-for-web2-auth/index.md
• Line: 40
• Change: Users have a a private key → Users have a private key

Related Issue

N/A - This is a simple typo fix that doesn't require a prior issue.

[netlify]

✅ Deploy Preview for ethereumorg ready!

Name	Link
🔨 Latest commit	2795040
🔍 Latest deploy log	https://app.netlify.com/projects/ethereumorg/deploys/69236579f019bd0008dbd01e
😎 Deploy Preview	https://deploy-preview-16689--ethereumorg.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
Lighthouse	7 paths audited Performance: 48 (🔴 down 11 from production) Accessibility: 94 (no change from production) Best Practices: 92 (🔴 down 7 from production) SEO: 91 (no change from production) PWA: 59 (no change from production) View the detailed breakdown and full score reports

---

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