Add a TLS scenario using Barbican

This patch adds a TLS load balancer scenario test using Barbican.

Story: 1627383
Task: 5149

Change-Id: I7013888f94261d94e1cd4c3167dc84da7125d1da
diff --git a/doc/requirements.txt b/doc/requirements.txt
index 467e820..d2e8cfc 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -2,7 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-sphinxcontrib-apidoc # BSD
+sphinxcontrib-apidoc>=0.2.0 # BSD
 sphinx>=1.6.2,!=1.6.6,!=1.6.7 # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0