MQE-1905: Inconsistent environment variable naming for MAGENTO_BACKEND_BASE_HOST

Author: jilu1

etc/config/.env.example

@@ -5,7 +5,7 @@
 MAGENTO_BASE_URL=http://devdocs.magento.com/
 
 #*** Uncomment if you are running Admin Panel on separate domain (used with MAGENTO_BACKEND_NAME) ***#
-# MAGENTO_BACKEND_BASE_HOST=http://admin.example.com/
+# MAGENTO_BACKEND_BASE_URL=http://admin.example.com/
 
 #*** Set the Admin Username and Password for your Magento instance ***#
 MAGENTO_BACKEND_NAME=admin