Add an examples of using UNC path in path.repo

Closes #12665

docs/reference/modules/snapshots.asciidoc

@@ -76,6 +76,14 @@ Assuming that the shared filesystem is mounted to `/mount/backups/my_backup`, th
 path.repo: ["/mount/backups", "/mount/longterm_backups"]
 --------------
 
+The `path.repo` setting supports Microsoft Windows UNC paths as long as at least server name and share are specified as
+a prefix and back slashes are properly escaped:
+
+[source,yaml]
+--------------
+repo.path: ["\\\\MY_SERVER\\Snapshots"]
+--------------
+
 After all nodes are restarted, the following command can be used to register the shared file system repository with
 the name `my_backup`: