Include xDS example's README.md when updating release tag version.
Include xDS example's README.md when updating release tag version.

stanley-cheung/grpc-java,dapengzhang0/grpc-java,ejona86/grpc-java,ejona86/grpc-java,stanley-cheung/grpc-java,dapengzhang0/grpc-java,grpc/grpc-java,dapengzhang0/grpc-java,stanley-cheung/grpc-java,ejona86/grpc-java,ejona86/grpc-java,stanley-cheung/grpc-java,grpc/grpc-java,dapengzhang0/grpc-java,grpc/grpc-java,grpc/grpc-java