Update quick start guide

Update to the 0.15.1 release

Signed-off-by: James Taylor <[email protected]>

Author: jt-nti

docs/getting-started/demo.md

@@ -28,7 +28,7 @@ Set the following environment variables to enable the k8s builder and define whi
 
 ```shell
 export TEST_NETWORK_CHAINCODE_BUILDER="k8s"
-export TEST_NETWORK_K8S_CHAINCODE_BUILDER_VERSION="0.15.0"
+export TEST_NETWORK_K8S_CHAINCODE_BUILDER_VERSION="0.15.1"
 ```
 
 ## Download chaincode samples