WEB: Accept PDEP-1
I forgot to accept PDEP-1 before merging #47444
Thanks @datapythonista  @datapythonista on https://pandas.pydata.org/about/roadmap.html there is a link to this PDEP. 

https://pandas.pydata.org/pdeps/accepted/0001-puropose-and-guidelines.html

That gives me a 404. Ah, I see now. The link was never updated after the change to a flat structure. Will put up a PR to fix.