Update JSON C++ example.

example/cpp/README.md

@@ -21,4 +21,4 @@ cmake --build .
 
 Documentation for all available classes and methods can be found at https://core.telegram.org/tdlib/docs.
 
-To run `tdjson_example` you may need to manually copy a `tdjson` shared library from `td/bin` to a directory containing built binaries.
+To run the examples you may need to manually copy needed shared libraries from `td/bin` to a directory containing built binaries.

example/cpp/tdjson_example.cpp

@@ -18,6 +18,9 @@ int main() {
   int client_id = td_create_client();
   // somehow share the client_id with other threads, which will be able to send requests via td_send
 
+  // start the client by sending request to it
+  td_send(client_id, "{\"@type\":\"getOption\", \"name\":\"version\"}");
+
   const bool test_incorrect_queries = false;
   if (test_incorrect_queries) {
     td_execute("{\"@type\":\"setLogVerbosityLevel\", \"new_verbosity_level\":1}");