update openhtmltopdf url (#1162)

Author: ko-sasaki

README.md

@@ -897,7 +897,7 @@ _Tools to help with PDF files._
 - [flyingsaucer](https://github.com/flyingsaucerproject/flyingsaucer) - XML/XHTML and CSS 2.1 renderer. (LGPL-2.1-or-later)
 - [iText ![c]](https://itextpdf.com/en) - Creates PDF files programmatically.
 - [JasperReports](https://community.jaspersoft.com/project/jasperreports-library) - Complex reporting engine. (LGPL-3.0-only)
-- [Open HTML to PDF](https://github.com/danfickle/openhtmltopdf) - Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.
+- [Open HTML to PDF](https://github.com/openhtmltopdf/openhtmltopdf) - Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.
 - [OpenPDF](https://github.com/LibrePDF/OpenPDF) - Open-source iText fork. (LGPL-3.0-only & MPL-2.0)
 - [Tabula](https://github.com/tabulapdf/tabula-java) - Extracts tables from PDF files.