Add Use case summery page for release notes

Issue-ID: INT-748

Change-Id: Ib22dba23854194be4052f869a40cea12d74dea4a
Signed-off-by: helenc878 <helen.chen@huawei.com>
diff --git a/docs/docs_vlb.rst b/docs/docs_vlb.rst
index 07671cd..ded308f 100644
--- a/docs/docs_vlb.rst
+++ b/docs/docs_vlb.rst
@@ -1,3 +1,5 @@
+.. _docs_vlb:
+
 vLoadBalancer Use Case
 ----------------------