Docs: write that users should call client.invoke({ _: 'close' }) instead of client.destroy() in most cases

[Bannerets]

tdlib/td#594 (comment), tdlib/td#771 (comment):

This is a sanity check that fires when app tries to destroy a client, which is still used in other thread by td_json_client_receive. You must first stop to use the client and only after that you can call td_json_client_destroy.

The usual way to do that is to call the method close, then wait for updateAuthoriationState with state authorizationStateClosed, stop calling td_json_client_receive and call td_json_client_destroy.

TDLib doesn't allow to call td_json_client_destroy while td_json_client_receive is running in another thread. It can happen in tdl, since it uses libuv threadpool to asynchronously call those methods.

So await client.invoke({ _: 'close' }) should be used instead of client.destroy() (which just calls internal td_json_client_destroy). tdl will call destroy automatically when it receives authorizationStateClosed.

Maybe client.destroy should be removed from the public interface in the next major version.