[ISSUE apache#862] Update client version in Readme file.

close apache#862

Author: ShannonDing

README.md

@@ -19,14 +19,15 @@ A product ready RocketMQ Client in pure go, which supports almost the full featu
 
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 ## Features
-For 2.0.0 version, it supports:
+For 2.X version, it supports:
 * sending message in synchronous mode
 * sending message in asynchronous mode
 * sending message in oneway mode
 * sending orderly messages
 * consuming message using push model
 * message tracing for pub and sub messages
 * ACL for producers and consumers
+* requset-reply model
 
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 ## How to use