use borg instead attic except at the places where it was used:
- as toplevel package name, directory name, file name
- to refer to original attic
remove sphinx upload make command, will be replaced by github.io site later
remove references to binary downloads and linux packages for now
remove some software name references, fix grammar
use borgbackup rather than borg-backup (or borg) in URLs,
less name collision issues, better search results, no validity issues with "-"
