doc(readme): update binary download link to 1.2.4

doc(readme): update binary download link to 1.2.4
diff --git a/doc/Introduction.md b/doc/Introduction.md
index 7a0ca09..60e70d8 100644
--- a/doc/Introduction.md
+++ b/doc/Introduction.md
@@ -16,7 +16,7 @@
 #### binary library
 your could download directly or build manually:
 
-- download specific release: [rocketmq-client-cpp](https://www.apache.org/dyn/closer.cgi?path=rocketmq/rocketmq-client-cpp/1.2.3/rocketmq-client-cpp-1.2.3-bin-release.tar.gz)
+- download specific release: [rocketmq-client-cpp](https://www.apache.org/dyn/closer.cgi?path=rocketmq/rocketmq-client-cpp/1.2.4/rocketmq-client-cpp-1.2.4-bin-release.tar.gz)
  and unzip the package, please choose the right version according to your OS and unzip it, then copy the library files to to your `LDFLAGS` directory(as default, `/usr/local/lib/` works finely).
  Please make sure your `LDFLAGS` directory is under the `LD_LIBRARY_PATH`.
 - build from source: [Build and Install](https://github.com/apache/rocketmq-client-cpp/tree/master#build-and-install)