(Azure CXP) Added clarifying sentence about port 80

Added "By default, App Service assumes your custom container is listening on port 80. "
https://github.com/MicrosoftDocs/azure-docs/issues/58553

articles/app-service/containers/configure-custom-container.md

@@ -14,7 +14,7 @@ This guide provides key concepts and instructions for containerization of Linux
 
 ## Configure port number
 
-The web server in your custom image may use a port other than 80. You tell Azure about the port that your custom container uses by using the `WEBSITES_PORT` app setting. The GitHub page for the [Python sample in this tutorial](https://github.com/Azure-Samples/docker-django-webapp-linux) shows that you need to set `WEBSITES_PORT` to _8000_. You can set it by running [`az webapp config appsettings set`](/cli/azure/webapp/config/appsettings?view=azure-cli-latest#az-webapp-config-appsettings-set) command in the Cloud Shell. For example:
+By default, App Service assumes your custom container is listening on port 80. The web server in your custom image may use a port other than 80. You tell Azure about the port that your custom container uses by using the `WEBSITES_PORT` app setting. The GitHub page for the [Python sample in this tutorial](https://github.com/Azure-Samples/docker-django-webapp-linux) shows that you need to set `WEBSITES_PORT` to _8000_. You can set it by running [`az webapp config appsettings set`](/cli/azure/webapp/config/appsettings?view=azure-cli-latest#az-webapp-config-appsettings-set) command in the Cloud Shell. For example:
 
 ```azurecli-interactive
 az webapp config appsettings set --resource-group <resource-group-name> --name <app-name> --settings WEBSITES_PORT=8000