update deltachat-jsonrpc readme

deltachat-jsonrpc/README.md

@@ -24,6 +24,21 @@ npm run build
 
 The JavaScript client is [published on NPM](https://www.npmjs.com/package/@deltachat/jsonrpc-client).
 
+###### Usage
+
+```typescript
+import { startDeltaChat } from "@deltachat/stdio-rpc-server";
+import { C } from "@deltachat/jsonrpc-client";
+
+const dc = await startDeltaChat("deltachat-data");
+console.log(await dc.rpc.getSystemInfo());
+const accounts = await dc.rpc.getAllAccounts()
+console.log('accounts', accounts)
+dc.close()
+```
+
+##### Generate TypeScript/JavaScript documentation
+
 A script is included to build autogenerated documentation, which includes all RPC methods:
 ```sh
 cd typescript