Update README.md

Author: nao-pon

README.md

@@ -21,7 +21,8 @@ used in Mac OS X operating system.
 [![Latest Stable Version](https://poser.pugx.org/studio-42/elfinder/version.png)](https://packagist.org/packages/studio-42/elfinder)
 [![Total Downloads](https://poser.pugx.org/studio-42/elfinder/d/total.png)](https://packagist.org/packages/studio-42/elfinder)
 [![CDNJS version](https://img.shields.io/cdnjs/v/elfinder.svg)](https://cdnjs.com/libraries/elfinder)
-[![Donate(nao-pon)](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FF5FKRSMKYDVA)
+[![Donate Paypal(nao-pon)](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FF5FKRSMKYDVA)
+[![Donate Bitcoin(nao-pon)](https://img.shields.io/badge/Donate-Bitcoin-orange.svg)](https://studio-42.github.io/elFinder/tools/donate-bitcoin/)
 
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