Update blueprint: admin notice (#121)

- Fixes #90 
- use login shorthand

This blueprint wouldn't get any value from using `writeFiles` as it only
writes one file.

---------

Co-authored-by: Bero <[email protected]>

Author: bph

blueprints/admin-notice/blueprint.json

@@ -7,12 +7,8 @@
 		"categories": ["Admin", "notices"]
 	},
 	"landingPage": "/wp-admin/plugins.php",
+	"login":true,
 	"steps": [
-		{
-			"step": "login",
-			"username": "admin",
-			"password": "password"
-		},
 		{
 			"step": "writeFile",
 			"path": "/wordpress/wp-content/mu-plugins/bgnightly-notice.php",