added env config instructions

ref #27

public/env.sample.js

@@ -1,10 +1,10 @@
 const config = {
 	// required
 	documentserver_key: '',
-	// required
+	// required, with trailing slash
 	baseurl: '',
-	// optional, will fallback to /selfservice
-	baseurl_selfservice: '/selfservice',
+	// optional, will fallback to /selfservice/
+	baseurl_selfservice: '/selfservice/',
 	// optional, will fallback to /imprint
 	url_imprint: '',
 	// optional, will fallback to /privacy