Fixed license in the readme file.
Fixed license in the readme file.

Bug: #14

pvginkel/PdfiumViewer,modulexcite/PdfiumViewer,MichalGrzegorzak/PdfiumViewer,pasysxa/PdfiumViewer,stevewangamm/PdfiumViewer,modulexcite/PdfiumViewer,pasysxa/PdfiumViewer,ballance/PdfiumViewer,MichalGrzegorzak/PdfiumViewer,stevewangamm/PdfiumViewer,ballance/PdfiumViewer,pvginkel/PdfiumViewer