Fix typo

remove unnecessary backslash on line 50.
*.www.msftncsi.com

Author: mattu0119

articles/backup/backup-configure-vault.md

@@ -47,7 +47,7 @@ The data that's available for backup depends on where the agent is installed.
 If your machine has limited internet access, ensure that firewall settings on the machine or proxy allow the following URLs and IP addresses:
 
 * URLs
-    * `www\.msftncsi.com`
+    * `www.msftncsi.com`
     * `*.Microsoft.com`
     * `*.WindowsAzure.com`
     * `*.microsoftonline.com`