right now, the update_usage script regenerates the usage files at
every call
by moving this into the makefile, we make those files be generated
only when the source file change, which makes testing docs much faster
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 "-"
