update pull request template

Author: yupwei68

.github/pull_request_template.md

@@ -5,8 +5,8 @@ Changes proposed in the pull request:
 
 Please add this into the test of test/fixture, format the changes by "terraform fmt", and test it by run the following:
 ```sh
-$ docker build --build-arg BUILD_ARM_SUBSCRIPTION_ID=$ARM_SUBSCRIPTION_ID --build-arg BUILD_ARM_CLIENT_ID=$ARM_CLIENT_ID --build-arg BUILD_ARM_CLIENT_SECRET=$ARM_CLIENT_SECRET --build-arg BUILD_ARM_TENANT_ID=$ARM_TENANT_ID -t azure-network-security-group .
-$ docker run --rm azure-network-security-group /bin/bash -c "bundle install && rake full"
+$ docker build --build-arg BUILD_ARM_SUBSCRIPTION_ID=$ARM_SUBSCRIPTION_ID --build-arg BUILD_ARM_CLIENT_ID=$ARM_CLIENT_ID --build-arg BUILD_ARM_CLIENT_SECRET=$ARM_CLIENT_SECRET --build-arg BUILD_ARM_TENANT_ID=$ARM_TENANT_ID -t azure-aks .
+$ docker run --rm azure-aks /bin/bash -c "bundle install && rake full"
 ```
 
 Please add this into the example usage of README.md and format the changes by "terrafmt fmt README.md".