Add separated section for extra specs and image properties

We should describe extra specs and image properties in concept doc
This patch add separated section for it.

blueprint complete-todo-in-api-concept-doc

Change-Id: I092c15c82666eeb113485aee3ea878888d6eaf2d

api-guide/source/extra_specs_and_properties.rst

@@ -0,0 +1,17 @@
+=======================================
+Flavor Extra Specs and Image Properties
+=======================================
+
+TODO: Generic description about Flavor Extra Specs and Image Properties.
+
+Flavor Extra Specs
+==================
+
+TODO: List the extra specs which we supported at here. The best is the extra
+specs can auto-gen from the nova code.
+
+Image Properties
+================
+
+TODO: List the properties which affect the server creation. The best is the
+properties can auto-gen from the image properties object.

api-guide/source/general_info.rst

@@ -39,6 +39,11 @@ several key concepts:
    unique combination of disk space, memory capacity and priority for
    CPU time.
 
+-  **Flavor Extra Specs**
+
+   TODO: Short description at here. The detail reference to
+   :doc:`extra_specs_and_properties`
+
 -  **Image**
 
    A collection of files used to create or rebuild a server. Operators
@@ -48,6 +53,11 @@ several key concepts:
    server images if you plan to deploy a particular server configuration
    frequently.
 
+-  **Image Properties**
+
+   TODO: Short description at here. The detail reference to
+   :doc:`extra_specs_and_properties`
+
 -  **Key Pair**
 
    An ssh or x509 keypair that can be injected into a server. This allows you