Add DG Appendix: Effort

[hjungwoo01]

From the website:
We highly recommend adding an appendix named Appendix: Effort that evaluators can use to estimate the total project effort.
Keep it brief (~1 page)
Explain the difficulty level, challenges faced, effort required, and achievements of the project.
If a significant part (e.g., more than 5%) of the effort was saved through reuse, mention what you reused and how it affected the effort e.g., the feature X is implemented using library Foo -- our work on adapting Foo to our product is contained in class FooAdapter.java.
Use AB3 as a reference point e.g., you can explain that while AB3 deals with only one entity type, your project was harder because it deals with multiple entity types.