add global exclude file for borg
add global exclude file for borg

to test
- |     mkdir -p exp && cd exp
  |     mkdir -p path/{lua_modules,repo/lib/.precomp}
  |     touch path/{.DS_Store,file.txt,lua_modules/{abc,def,ghi}.txt,repo/lib/.DS_Store}
  |     touch path/repo/lib/.precomp/$(sha256sum path/file.txt | cut -c -64)
  |     borg create \
  |       --list \
  |       --dry-run \
  |       --exclude-from "$HOME/.config/borg/exclude" \
  |       mock-repo::mock-archive \
  |       path

see also: `borg help patterns`

atweiden/macfiles