Update Axum https example (#186)

* Add rust axum https example

* Update SAM template

Author: bnusunny

examples/rust-axum-https-zip/template.yaml

@@ -46,4 +46,4 @@ Resources:
 Outputs:
   AxumHttpApi:
     Description: "API Gateway Http API endpoint URL for default stage for Axum function"
-    Value: !Sub "https://${HttpApi}.execute-api.${AWS::Region}.${AWS::URLSuffix}/"
+    Value: !Sub "https://${ServerlessHttpApi}.execute-api.${AWS::Region}.${AWS::URLSuffix}/"