docs: Add more on trex

Change-Id: Ifb5eabe30e1b0ba911ddf455573cc346ff4bec85
Signed-off-by: jdenisco <jdenisco@cisco.com>
diff --git a/docs/usecases/index.rst b/docs/usecases/index.rst
index e6287f3..735947c 100644
--- a/docs/usecases/index.rst
+++ b/docs/usecases/index.rst
@@ -14,3 +14,5 @@
    vhost/index.rst
    homegateway
    contiv/index.rst
+
+