Identify external domains

[jtagcat]

Is your feature request related to a problem? Please describe.
Don't know what really breaks the site where.

Describe the solution you'd like
Add two fields:

• Category
• Brief description / label

Sentry:

• Telemetry
• Error logging

AdWords:

• Ads
• Google

githubassets:

• CDN
  • github.com (see also List: First-Party isolation CDNs #26)
• (no label)

This allows making better guesses on what is likely required for the site to function.

Describe alternatives you've considered
Opening the domains listed, or randomly guessing.