feat(tiered-pricing): add missing examples to readme

Author: santakadev

exercises/tiered_pricing/README.md

@@ -29,6 +29,8 @@ development process:
 | 1             |      299 € | 299 €  |
 | 2             |      299 € | 598 €  |
 | 3             |      239 € | 717 €  |
+| 4             |      239 € | 956 €  |
+| 5             |      239 € | 1195 € |
 | 11            |      219 € | 2409 € |
 | 12            |      219 € | 2628 € |
 | 13            |      219 € | 2847 € |