Review Companion should show summary of changes

[caugner]

What type of issue is this?

Infrastructure issue

What is the issue?

In https://github.com/mdn/browser-compat-data/pull/28637#pullrequestreview-3567886593, most features tagged with web-features:attribution-reporting were changed, but not all.

The only way to find this is out was to manually search for the web-features tag, and check each feature.

What behavior were you expecting?

It would have been extremely helpful if the review companion comment would have included a comment like this:

web-features

• attribution-reporting (84 % features updated / 16 of 19)

What version(s) of BCD is the issue present in?

• [ ] The current BCD release
• [ ] The current version of the main branch

Do you have anything more you want to share?

Break downs by browser would also be interesting.