Adjust pull_request_template.md...

- Provide details on PR dependencies
- Call out the bulleted list

.github/pull_request_template.md

@@ -4,9 +4,7 @@
 ## Details
 <!-- If you feel it is helpful, list the changes made -->
 
-- 
--
--
+- Bulleted list with explanations
 
 ## Testing
 <!-- How did you test this? 
@@ -17,7 +15,10 @@
 
 ## Dependencies
 <!-- If this PR relies on other PRs not yet merged to main, 
-    mention and link them here. Delete if there are none -->
+    mention and link them here. Delete if there are none.
+    If this is dependent on exactly _one_ PR, mark that as the
+    merge target of this PR. GitHub will automatically update
+    the merge target once the dependent PR is merged. -->
 
 ## Future Work
 <!-- Discuss things that should be done in the future,