Added readme

README.md

+## Telegram messenger for Android
+
+[Telegram](http://telegram.org) is a messaging app with a focus on speed and security. It’s superfast, simple and free.
+
+This repo contains official [Telegram App for Android](https://play.google.com/store/apps/details?id=org.telegram.messenger) source code.
+
+### API, Protocol documentation
+
+Documentation for Telegram API is available here: http://core.telegram.org/api
+
+Documentation for MTproto protocol is available here: http://core.telegram.org/mtproto
+
+### Usage
+
+Import the root folder into your IDE (tested on Android Studio), then run project.