Updates index.md to fix verb conjugation

[jpgninja]

Small change to fix typo. Original:

This makes it useful for build a workflow to process data and return the results, like an API endpoint.

Update:

This makes it useful for building a workflow to process data and return the results, like an API endpoint.

[CLAassistant]

All committers have signed the CLA.

[netlify]

✅ Deploy Preview for n8n-docs ready!

Name	Link
🔨 Latest commit	c5f8724
🔍 Latest deploy log	https://app.netlify.com/sites/n8n-docs/deploys/67c74ad23c46640008ecf61a
😎 Deploy Preview	https://deploy-preview-2937--n8n-docs.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.

[imchairmanm]

Great catch, thanks for the PR!