Update Dockerfile to 4.6.2 on branch-4.6 (#1320)

diff --git a/docker/Dockerfile b/docker/Dockerfile
index a76a6d9..6dd3aa4 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -20,7 +20,7 @@
 FROM centos:7
 MAINTAINER Apache BookKeeper <dev@bookkeeper.apache.org>
 
-ARG BK_VERSION=4.6.1
+ARG BK_VERSION=4.6.2
 ARG DISTRO_NAME=bookkeeper-server-${BK_VERSION}-bin
 ARG GPG_KEY=A615D22C