Added paypal-button

Author: zyberspace

README.md

@@ -5,6 +5,7 @@ php-client for [telegram-cli](https://github.com/vysheng/tg/)
 [![Packagist](https://img.shields.io/packagist/v/zyberspace/telegram-cli-client.svg)](https://packagist.org/packages/zyberspace/telegram-cli-client)
 [![Codacy](https://www.codacy.com/project/badge/4175a9bbf88547cdbd94cf57c457068d)](https://www.codacy.com/app/zyberspace/php-telegram-cli-client)
 [![License](https://img.shields.io/github/license/zyberspace/php-telegram-cli-client.svg)](https://www.mozilla.org/MPL/2.0/)
+[![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_SM.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=9FC7BR6XPXFLE)
 
 Requirements
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