Add Policy Executor Open API Interface definition

- OPenApi in RTD only (for now)
- Bear authentication included in OpenApi
- Placeholder RTD page (to be completed upon feature delivery)
- For consistency (and color coding in editors) I put all Description and Example strings inside double qoutes "..."

Issue-ID: CPS-2291
Change-Id: I7f16cdce2a06cb011997005fa8b86b54c044304a
Signed-off-by: ToineSiebelink <toine.siebelink@est.tech>
diff --git a/docs/design.rst b/docs/design.rst
index af1f5ab..52f977a 100644
--- a/docs/design.rst
+++ b/docs/design.rst
@@ -60,11 +60,20 @@
 Consumed APIs
 =============
 
-CPS Core uses API's from the following ONAP components
+DMI-Plugin
+----------
 
-* DMI-Plugin: REST based interface which is used to provide integration
-  and allow the DMI registry API's have access to the corresponding NCMP API's within CPS Core.
-  More information on the DMI-Plugins offered APIs can be found on the :ref:`DMI-Plugin's Design Page <onap-cps-ncmp-dmi-plugin:design>`.
+DMI-Plugin is a REST based interface which is used to provide integration
+and allow the DMI registry API's have access to the corresponding NCMP API's within CPS Core.
+More information on the DMI-Plugins offered APIs can be found on the :ref:`DMI-Plugin's Design Page <onap-cps-ncmp-dmi-plugin:design>`.
+
+Policy-Executor
+---------------
+
+.. toctree::
+   :maxdepth: 1
+
+   policy-executor.rst
 
 CPS Path
 ========