Create Promenade API documentation

Creates outline and documentation of Promenade API to be created
in future patchsets.

Change-Id: I6ef2cded840e2c48a3152bd4316b88c8e50f1da6

docs/source/api.rst

@@ -0,0 +1,62 @@
+Promenade API
+=============
+
+
+/v1.0/health
+------------
+
+Allows other components to validate Promenade's health status.
+
+GET /v1.0/health
+
+Returns the health status.
+
+Responses
+- 204 No Content
+
+
+/v1.0/join-scripts
+------------------
+
+Generates join scripts and for Drydock.
+
+GET /v1.0/join-scripts
+
+Generates script to be consumed by Drydock.
+
+Query parameters
+hostname
+    Name of the node
+ip
+    IP address of the node
+design_ref
+    Endpoint containing configuration documents
+dynamic.labels
+    Used to set configuration options in the generated script
+static.labels
+    Used to set configuration options in the generated script
+
+Responses
+- 204 No Content: Scripts generated successfully
+- 400 Bad Request: One or more query parameters is missing or misspelled
+
+
+/v1.0/validatedesign
+--------------------
+
+Performs validations against specified documents.
+
+POST /v1.0/validatedesign
+
+Performs validation against specified documents.
+
+Message Body
+href
+    Location of the document to be validated
+type
+    Type of document to be validated
+
+Responses:
+- 200 OK: Documents were successfully validated
+- 400 Bad Request: Documents were not successfully validated
+- 404 Not Found: The document (of that type) was not found at the specified location