document application filtering

Change-Id: I6d74171df4afbcb3215e9a6ca7db3981d5baa157
diff --git a/index.rst b/index.rst
index 784eb4d..418df2a 100644
--- a/index.rst
+++ b/index.rst
@@ -70,6 +70,7 @@
    operations/procedures
    operations/subscriber
    operations/vcs
+   advanced/appfilter
 
 .. toctree::
    :maxdepth: 3