fix: typos in systemd module (#40)

* module systemd: fix typos in README.md

* module systemd: fix typos in systemd.sh

modules/systemd/README.md

@@ -7,14 +7,14 @@ The `systemd` module streamlines the management of systemd units during image bu
 ```yaml
 type: systemd
 system:
-  enable:
+  enabled:
     - example.service
-  disable:
+  disabled:
     - example.target
 user:
-  enable:
+  enabled:
     - example.timer
-  disable:
+  disabled:
     - example.service
 ```
 

modules/systemd/systemd.sh

@@ -22,13 +22,13 @@ if [[ ${#DISABLED[@]} -gt 0 ]]; then
     done
 fi
 if [[ ${#USER_ENABLED[@]} -gt 0 ]]; then
-    for unit in "${ENABLED[@]}"; do
+    for unit in "${USER_ENABLED[@]}"; do
         unit=$(printf "$unit")
         systemctl --user enable $unit
     done
 fi
 if [[ ${#USER_DISABLED[@]} -gt 0 ]]; then
-    for unit in "${DISABLED[@]}"; do
+    for unit in "${USER_DISABLED[@]}"; do
         unit=$(printf "$unit")
         systemctl --user disable $unit
     done