Add the 1.9 release notice in README (#20806)
Add the 1.9 release notice in README (#20806)


szha/mxnet,szha/mxnet,szha/mxnet,szha/mxnet,DickJC123/mxnet,szha/mxnet,DickJC123/mxnet,szha/mxnet,apache/incubator-mxnet,apache/incubator-mxnet,szha/mxnet,apache/incubator-mxnet,DickJC123/mxnet,szha/mxnet,DickJC123/mxnet,szha/mxnet,apache/incubator-mxnet