Start documentation on web_portal.md

docs/web_portal.md

 # Web Portal
+
+## Default Instance
+
+When you first connect to [localhost:4200](http://localhost:4200/), you should
+see the default instance implemented. Note that there is a default re-routing
+to `./portal/home/`.
+
+You can click on `Access to the project` to go to the homepage of the instance.