cleanup and grammarly

Author: dawnkelly09

parachains/customize-runtime/pallet-development/.nav.yml

@@ -1,6 +1,6 @@
 nav:
  - 'Create a Custom Pallet': create-a-pallet.md
  - 'Mock Your Runtime': mock-runtime.md
- - 'Pallet Unit Testing': pallet-testing.md
+ - 'Unit Test Pallets': pallet-testing.md
  - 'Add a Custom Pallet to Your Runtime': add-pallet-to-runtime.md
  - 'Benchmark a Custom Pallet': benchmark-pallet.md