Update download.md: add integration monitor

[patmmccann]

🏷 Type of documentation

• new bid adapter
• update bid adapter
• new feature
• text edit only (wording, typos)
• bugfix (code examples)
• new examples

📋 Checklist

• Related pull requests in prebid.js or server are linked -> Paste link in this list or reference it on the PR itself
• For new adapters check submitting your adapter docs

[netlify]

✅ Deploy Preview for prebid-docs-preview ready!

Name	Link
🔨 Latest commit	c3fc53d
🔍 Latest deploy log	https://app.netlify.com/sites/prebid-docs-preview/deploys/66feb551cee722000897e0cb
😎 Deploy Preview	https://deploy-preview-5631--prebid-docs-preview.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.

[bretg]

Sorry, but this page is too unfriendly to place on the popular downloads page.

It's not obvious at all that you have to download a static file, then re-upload it to this page. If this data isn't going to change frequently, then the data and graphs should just be copied to a page in the docs repo. If it is going to change somewhat often, then we need to find some way to get the appropriate file fed into this page's javascript without the head scratching.