Remove placeholder links from pull_request_template.md (#3502)

Author: mdaigle

.github/pull_request_template.md

@@ -14,8 +14,8 @@ High quality descriptions will lead to a smoother review experience.
 
 ## Issues
 
-Link to any relevant issues, bugs, or discussions (e.g., "Closes \#123", "Fixes
-issue \#456").
+Link to any relevant issues, bugs, or discussions (e.g., `Closes #123`, `Fixes
+issue #456`).
 
 ## Testing