Merge pull request #798 from jyn514/intructions

Suggest looking at detailed-query page for rollups

Author: Mark-Simulacrum

triage/README.md

@@ -63,6 +63,7 @@ Difficult cases: the merge was a rollup of multiple PRs.
 - Look through the PRs and try to determine which was the cause. Often you
   can easily tell that one or more PRs could not have caused the change, e.g.
   because they made trivial changes, documentation-only changes, etc.
+- If there are still PRs left over, look at the 'detailed-query' page on perf.rlo: often, there is a single timing pass that improved significantly, and the name may give you a hint. You can find the page by expanding the dropdown for the build with the greatest change, then clicking on the percent change. Note that this does not work for `-doc` builds.
 - If you can't narrow it down to a single PR, in the rollup PR ask all the
   authors who might be responsible.
 - Once you have narrowed it down to a single PR, treat it like an easy case,