change URL format for hostName description (#19204)

Author: tfitzmac

specification/datafactory/resource-manager/Microsoft.DataFactory/stable/2018-06-01/datafactory.json

@@ -5277,7 +5277,7 @@
       ],
       "properties": {
         "hostName": {
-          "description": "GitHub Enterprise host name. For example: https://github.mydomain.com",
+          "description": "GitHub Enterprise host name. For example: `https://github.mydomain.com`",
           "type": "string"
         },
         "clientId": {