Adding Documentation regarding PRH

Change-Id: I158a97dbdf06297c1cacae2da6a318adf6218a96
Issue-ID: DCAEGEN2-398
Signed-off-by: pwielebs <piotr.wielebski@nokia.com>
diff --git a/docs/sections/services/prh/architecture.rst b/docs/sections/services/prh/architecture.rst
new file mode 100644
index 0000000..c47772a
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+++ b/docs/sections/services/prh/architecture.rst
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+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. http://creativecommons.org/licenses/by/4.0
+
+PRH Architecture
+===================
+
+**PRH** is a new DCAE micro-service which participates in the Physical Network Function Plug and Play (PNF PnP)
+procedure. PNF PnP is used to register PNF when it comes online.
+
+PRH Processing Flow
+===================
+
+.. image:: ../../images/prhAlgo.png
+
+