update docs

Author: ASKozienko

docs/client/rpc_call.md

@@ -43,7 +43,7 @@ $promises[] = $rpcClient->callAsync('greeting_topic', 'Hi Thomas!', 5);
 
 $replyMessages = [];
 foreach ($promises as $promise) {
-    $replyMessages[] = $promise->getMessage();
+    $replyMessages[] = $promise->receive();
 }
 ```
 

docs/quick_tour.md

@@ -124,7 +124,7 @@ $message = $psrContext->createMessage('Hi there!');
 $rpcClient = new RpcClient($psrContext);
 
 $promise = $rpcClient->callAsync($queue, $message, 1);
-$replyMessage = $promise->getMessage();
+$replyMessage = $promise->receive();
 ```
 
 There is also extensions for the consumption component.