Add screenshot for create flavor

As 'Create Flavor' has many parameters, provide a screenshot can make
the description of parameters more distinct. And also make consistent
with 'Create Image' in 'http://docs.openstack.org/user-guide-admin/dashboard_manage_images.html'

Change-Id: I74f123ab43a5ce15e9b0eaf00188d70d878ec014

doc/admin-guide-cloud/source/dashboard_manage_flavors.rst

@@ -31,6 +31,10 @@ Create flavors
 #. In the :guilabel:`Create Flavor` window, enter or select the
    parameters for the flavor in the :guilabel:`Flavor Information` tab.
 
+   .. figure:: figures/create_flavor.png
+
+   **Dashboard — Create Flavor**
+
    =========================  =======================================
     **Name**                   Enter the flavor name.
     **ID**                     Unique ID (integer or UUID) for the

doc/admin-guide-cloud/source/dashboard_manage_volumes.rst

@@ -57,6 +57,8 @@ Create an encrypted volume type
 
 #. Click :guilabel:`Create Volume Type Encryption`.
 
+.. figure:: figures/create_volume_type_encryption.png
+
 **Encryption Options**
 
 The table below provides a few alternatives available for creating encrypted

doc/user-guide-admin/source/dashboard_manage_flavors.rst

@@ -31,6 +31,10 @@ Create flavors
 #. In the :guilabel:`Create Flavor` window, enter or select the
    parameters for the flavor in the :guilabel:`Flavor Information` tab.
 
+   .. figure:: figures/create_flavor.png
+
+   **Dashboard — Create Flavor**
+
    =========================  =======================================
     **Name**                   Enter the flavor name.
     **ID**                     Unique ID (integer or UUID) for the

doc/user-guide-admin/source/dashboard_manage_volumes.rst

@@ -57,6 +57,8 @@ Create an encrypted volume type
 
 #. Click :guilabel:`Create Volume Type Encryption`.
 
+.. figure:: figures/create_volume_type_encryption.png
+
 **Encryption Options**
 
 The table below provides a few alternatives available for creating encrypted