Using copilot to help understand PR build failures

Author: trask

CONTRIBUTING.md

@@ -89,6 +89,9 @@ https://gradle.com/s/ila4qwp5lcf5s
 Opening the build scan link can sometimes take several seconds (it's a large build), but it
 typically makes it a lot clearer what's failing.
 
+You can also try the "Explain error" button at the top of the GitHub Actions page,
+which often does a reasonable job of parsing the long build log and displaying the important part.
+
 ### Draft PRs
 
 Draft PRs are welcome, especially when exploring new ideas or experimenting with a hypothesis.