changed it to english

Author: munkhuushmgl

speech/cloud-client/README.md

@@ -159,7 +159,7 @@ Continuously stream audio to the speech API over multiple requests (by default e
 ```
 mvn exec:java -DInfiniteStreamRecognize
 ```
-If stream audio is in different language, you could also pass language code as a command line argument (for example, korea).
+If stream audio is in different language, you could also pass language code as a command line argument (for example, en-GB for english (Great Britian), en-US for english U.S., and more available in [this link](https://cloud.google.com/speech-to-text/docs/languages)).
 ```
-mvn exec:java -Dexec.args="-lang_code=ko-KR" -DInfiniteStreamRecognize
+mvn exec:java -Dexec.args="-lang_code=en-US" -DInfiniteStreamRecognize
 ```