add readme as intro page

.mattrbld/config.json

@@ -13,7 +13,19 @@
       "protected": true
     },
     {
-      "label": "Media Library",
+      "separator": true,
+      "target": {
+        "name": "Project.Documentation",
+        "params": {
+          "path": "/README.md"
+        }
+      },
+      "icon": "error",
+      "showInDashboard": true,
+      "label": "Intro and help"
+    },
+    {
+      "label": "Media library",
       "icon": "image-stack",
       "target": {
         "name": "Project.MediaLibrary"