[Gnso-rds-pdp-3] Revised document

I revised the document significantly from Alex’s version, but the majority of the changes are simply to remove operational and template material (such as descriptions of timelines, etc.) I have made some changes to the group conclusions in the document, but I hope that I have not included anything not specifically on the call. Please let me know if you think any changes need to be made very quickly - other wise this draft will be sent to the working group in a few hours, David