Restructure CLAMP documentation tree

Restructured and refactored the CLAMP documentation
- Introduced a hierarchical structure to the documentaiton
- Added a tree for builtin and TOSCA CLAMP
- Cleaned up formatting
- Added documentation for participants
- Added placeholders for missing particioant, control loop runtime,
  and control loop GUI documentation
- Fixed some hanging references

Issue-ID: POLICY-3363
Change-Id: I3933be08af3984f2bb4e08707a8c5b5b454f540c
Signed-off-by: liamfallon <liam.fallon@est.tech>

1 files changed, 39 insertions, 0 deletions

diff --git a/docs/clamp/controlloop/design-impl/participants/participants.rst b/docs/clamp/controlloop/design-impl/participants/participants.rst
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+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+
+.. _clamp-controlloop-participants:
+
+Control Loop Participants
+#########################
+
+A Participant is a component that acts as a bridge between the CLAMP COntrol Loop runtime and components such as
+the Policy Framework, DCAE, or a Kubernetes cluster that are taking part in control loops. It listens
+to DMaaP to receive messages from the CLAMP runtime and performs operations towards components that
+are taking part in control loops. A participant has a Control Loop Element for each control loop in
+which it is taking part.
+
+The implementation of a participant may use a common
+:ref:`Participant Intermediary library <clamp-controlloop-participant-intermediary>`, which carries out common
+message and state handling for Control Loop Elements in participants. The *ParticipantImpelementation* is the
+component specific implementation of a participant, which is specifically developed for each component that
+wishes to take part in control loops.
+
+.. image:: ../../images/participants/participants.png
+
+The figure above shows participants for various components that may take part in control loops.
+
+.. note:: The figure above is for illustration. Not all the participants mentioned above
+          have realizations in ONAP. Some of the participants in the figure above represent
+          a type of participant. For example, a controller participant would be written for
+          a specific controller such as CDS and a participant for an existing system would be
+          written towards that existing system.
+
+The detailed implementation of the CLAMP Participant ecosystem is described on the following pages:
+
+.. toctree::
+   :maxdepth: 1
+
+   participant-intermediary
+   http-participant
+   k8s-participant
+   policy-framework-participant
+   participant-simulator