chore: typo

Author: QingWei-Li

.github/PULL_REQUEST_TEMPLATE.md

@@ -2,4 +2,4 @@ Please makes sure these boxes are checked before submitting your PR, thank you!
 
 * [ ] Make sure you are merging your commits to `master` branch.
 * [ ] Add some descriptions and refer relative issues for you PR.
-* [ ] DO NOT include files inside lib directory.
+* [ ] DO NOT include files inside `lib` directory.