deploy.sh: print usage message

deploy.sh

@@ -1,5 +1,13 @@
 #!/bin/sh
 
+usage () {
+    {
+        echo "Usage: $0 [--vagrant]"
+        echo "Usage: $0 [--vagrant] base"
+        echo "Usage: $0 [--vagrant] services [SERVICE]"
+    } >&2
+}
+
 BASE_CMD="ansible-playbook playbook.yml --ask-vault-pass"
 
 if [ "$1" = "--vagrant" ]; then
@@ -30,7 +38,7 @@ else
             $BASE_CMD --tags base_only
         ;;
         *)
-            echo >&2 "Command \"$1\" not found!"
+            usage
             exit 1
         ;;
     esac