Update README.md

Improved Readme

README.md

-telegram-client. Uses readline interface.
+## Telegram messenger CLI
+
+Command-line interface for [Telegram](http://telegram.org). Uses readline interface.
+
+### 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
+
+### Installation
+
+Just run `make`
+
+### Usage
+
+    ./telegram -k <public-server-key>
+    
+By default public key is stored in the same folder named tg.pub:
+
+    ./telegram -k tg.pub
+  
+#### Supported commands:
+
+* chat_info
+* contact_list
+* dialog_list
+* help
+* history
+* msg
+* send_photo
+* send_text
+* send_video
+* stats
 
-usage: telegram -k <public-server-key>