AETHER-3049 add metering documentation

Change-Id: I26d8fc60a0e30f7f484f6f0ffe2c5bb581486f1b
diff --git a/index.rst b/index.rst
index 34e22e2..28e8c4a 100644
--- a/index.rst
+++ b/index.rst
@@ -71,6 +71,7 @@
    operations/subscriber
    operations/vcs
    advanced/appfilter
+   advanced/metering
 
 .. toctree::
    :maxdepth: 3