AETHER-3210 subscriber proxy documentation

Change-Id: Ib729558b7ed356f076b73bd2fa2362115c491514
diff --git a/index.rst b/index.rst
index 28e8c4a..97d4a4b 100644
--- a/index.rst
+++ b/index.rst
@@ -72,6 +72,7 @@
    operations/vcs
    advanced/appfilter
    advanced/metering
+   advanced/subproxy
 
 .. toctree::
    :maxdepth: 3