overhauls of most service docs

active/systemd_borg/backup.sh.j2

@@ -33,6 +33,7 @@ borg create                         \
     --exclude-caches                \
     --exclude 'home/*/.cache/*'     \
     --exclude 'var/tmp/*'           \
+    --exclude 'home/*/.snapshots/*' \
 {% for dir in exclude_dirs %}
     --exclude '{{ dir }}' \
 {% endfor %}