Update PULL_REQUEST_TEMPLATE.md

Fix typos and make the checklist into an actual checklist

Author: claydiffrient

Diff for: .github/PULL_REQUEST_TEMPLATE.md

@@ -9,8 +9,8 @@ Upgrade Path (for changed or removed APIs):
 
 
 Acceptance Checklist:
-[ ] All commits have been squashed to one.
-[ ] The commit message follows the guidlines in `CONTRIBUTING.md`.
-[ ] Documentation (README.md) and examples have been updated as needed.
-[ ] If this is a code change, a spec testing the functionality has been added.
-[ ] If the commit message has [changed] or [removed], there is an upgrade path above.
+- [ ] All commits have been squashed to one.
+- [ ] The commit message follows the guidelines in `CONTRIBUTING.md`.
+- [ ] Documentation (README.md) and examples have been updated as needed.
+- [ ] If this is a code change, a spec testing the functionality has been added.
+- [ ] If the commit message has [changed] or [removed], there is an upgrade path above.