Add missing line continuation in example terraform init command

Author: ppejovic

examples/gitlab-managed-state/README.md

@@ -32,7 +32,7 @@ $ terraform init \
     -backend-config="password=${ACCESS_TOKEN}" \
     -backend-config="lock_method=POST" \
     -backend-config="unlock_method=DELETE" \
-    -backend-config="retry_wait_min=5"
+    -backend-config="retry_wait_min=5" \
     -backend-config="password=${ACCESS_TOKEN}"
 ```