[DOCS] new official source for "Adobe PDF Reference" (PDF32000_2008.pdf)

[tobwen]

Adobe published the Adobe PDF Reference document (PDF32000_2008.pdf) on Github and Github pages!

https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/pdfstandards/pdf/PDF32000_2008.pdf

resolves to

https://github.com/adobe/dc-acrobat-sdk-docs/blob/master/docs/standards/pdfstandards/pdf/PDF32000_2008.pdf

[JorjMcKie]

Thank you for the information!