Add basically API documentation

src/api/schema.ts

@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 Jonas Lochmann
+ * Copyright (C) 2019 - 2020 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -141,3 +141,4 @@ export interface SignInByMailCodeRequest {
 }
 
 export { SerializedParentAction, SerializedChildAction, SerializedAppLogicAction } from '../action/serialization'
+export { ServerDataStatus } from '../object/serverdatastatus'