[DOCS] How to reuse the client

[chungwong]

Please describe the documentation
It not clear how to reuse a client.

let client = Elasticsearch::default();
for _ in 0..10 {
 //               vvvvvvvvvvv cloning, should it?
  send_away(client.clone()).await;
}

The cloning on reqwest::Client is cheap enough but I am not sure the general idea on cloning ElaticSearch, there is credentials which basically just String

Describe where the documentation should for
If it works the same way as reqwest::Client, then a direct copy from reqwest is good enough

You do not have to wrap the Client in an Rc or Arc to reuse it, because it already uses an Arc internally.