Add postinstall instructions

CloudronManifest.json

@@ -29,14 +29,15 @@
   "developmentMode": false,
   "minBoxVersion": "0.80.0",
   "manifestVersion": 1,
-  "website": "https://taiga.io/",
+  "website": "https://taiga.io",
   "contactEmail": "support@cloudron.io",
-  "icon": "logo.png",
+  "icon": "file://logo.png",
   "mediaLinks": [
     "https://i.imgur.com/lwD0kKR.png",
     "https://i.imgur.com/mgQu5QD.png",
     "https://i.imgur.com/YMXzySO.png",
     "https://i.imgur.com/zMEzCHv.png",
     "https://i.imgur.com/muT1pMw.png"
-  ]
+  ],
+  "postInstallMessage": "file://POSTINSTALL.md"
 }

POSTINSTALL.md

@@ -0,0 +1,17 @@
+This app instance is pre-setup with an admin account.
+
+The initial credentials are:
+
+`username: admin`
+
+`password: 123123`
+
+**Please change the admin password on first login**
+
+=== sso ===
+
+This app integrates with Cloudron authentication. Cloudron users can login and use Taiga.
+
+However, _admin_ status of Cloudron users is not carried over to Taiga but is also not required for a working setup.
+
+The public registration is disabled, if required, please install an instance of Taiga without Cloudron user integration.