diff --git a/docs/guides/onap-developer/developing/index.rst b/docs/guides/onap-developer/developing/index.rst
index 0978edc..483dae3 100644
--- a/docs/guides/onap-developer/developing/index.rst
+++ b/docs/guides/onap-developer/developing/index.rst
@@ -252,6 +252,7 @@
    :titlesonly:
 
    ../../../submodules/policy/engine.git/docs/index
+   ../../../submodules/policy/apex-pdp.git/docs/index
 
 Portal Platform
 ---------------