Add external link checking exclusions

[jason-seqera]

This adds some exclusions:

exclude = [
  '^https://portal.azure.com/.+$',
  '^https://gitlab.com/profile/personal_access_tokens'
]

[netlify]

✅ Deploy Preview for seqera-docs ready!

Name	Link
🔨 Latest commit	8c8029a
🔍 Latest deploy log	https://app.netlify.com/sites/seqera-docs/deploys/66b100bf61906e00091c0ded
😎 Deploy Preview	https://deploy-preview-136--seqera-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.

[jason-seqera]

This seems to work, matched URLs do seem to be ignored.

| ## Summary
| 
| | Status        | Count |
| |---------------|-------|
| | 🔍 Total      | 15    |
| | ✅ Successful | 3     |
| | ⏳ Timeouts   | 0     |
| | 🔀 Redirected | 0     |
| | 👻 Excluded   | 12    |
| | ❓ Unknown    | 0     |
| | 🚫 Errors     | 0     |

[justinegeffen]

Thanks, @jason-seqera! Ready to merge. :)