No README and Chater 4 started

- [x] No README.md
- [X] Chapter 4 Started
1) There is nothing in the []. I don't think it works but Hashan does, so maybe add what is displayed when you hover over it.
2) Why copy a picture directly from Android's website? Make it yourself thereby removing the chance of copyright infringement. Or, if you can't be bothered, get someone else to do it. At least put a version in the Images folder.