Add screenshots to README

Author: Plastix

README.md

@@ -1,2 +1,11 @@
 # Buzz
 Spelling Bee game for Android
+![playstore_promo](https://user-images.githubusercontent.com/1526881/114287756-59218f00-9a1e-11eb-8e65-e94799d20772.png)
+
+
+
+## Screenshots
+| | | |
+|--|--|--|
+| ![image](https://user-images.githubusercontent.com/1526881/114287838-33e15080-9a1f-11eb-8afd-7582f2fcddec.png) | ![image](https://user-images.githubusercontent.com/1526881/114287844-4196d600-9a1f-11eb-86ca-3aae4f0a8f2d.png) | ![image](https://user-images.githubusercontent.com/1526881/114287852-4d829800-9a1f-11eb-8b6f-eedc01e9d823.png) | 
+| ![image](https://user-images.githubusercontent.com/1526881/114287842-39d73180-9a1f-11eb-815a-327f07e66610.png) | ![image](https://user-images.githubusercontent.com/1526881/114287847-45c2f380-9a1f-11eb-8d1b-3f8ea46674e6.png) | ![image](https://user-images.githubusercontent.com/1526881/114287854-54110f80-9a1f-11eb-81ca-5efdc9a2f4a9.png) |