OZG-6891 KOP-2735 javadoc: Explain xta client

src/main/java/de/ozgcloud/xta/client/XtaClient.java

@@ -192,7 +192,8 @@ public class XtaClient {
 	 * Sends the given message.
 	 *
 	 * <p>
-	 * Author and reader identifiers are taken from the message metadata. The message is sent to the reader.
+	 * Sends the message to the XTA server such that it may be asynchronously fetched by the reader. Author and reader of the message are given by the
+	 * message metadata.
 	 * </p>
 	 * <p>
 	 * First, checks whether the author refers to an active account. Then, checks that the service used by the message is available for the given