Updated from global requirements

Change-Id: I8b54ea50f36eca2a180d394878685e5866971cfc
diff --git a/doc/requirements.txt b/doc/requirements.txt
index 555b7d2..597b54e 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,6 +1,6 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-openstackdocstheme>=1.17.0 # Apache-2.0
+openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 sphinx!=1.6.6,>=1.6.2 # BSD