Update the PR template QA instructions to 1) make it clear that authors are responsible for testing their PRs, and 2) encourage sufficient detail in the QA section.

Author: RyanJDick

.github/pull_request_template.md

@@ -8,7 +8,7 @@
 
 ## QA Instructions
 
-<!--WHEN APPLICABLE: Describe how we can test the changes in this PR.-->
+<!--WHEN APPLICABLE: Describe how you have tested the changes in this PR. Provide enough detail that a reviewer can reproduce your tests.-->
 
 ## Merge Plan