[training] reorganizing image file names

Previous image file names (e.g., image00.png) were difficult to
follow with documents, since the image file name did not deliver
meaningful context. This commit changes the name of image files
by adding appropriate descriptions.

Note that other image files are needed to further identify where
they will be used or deleted.

Change-Id: I0a1b0f9d10fafd1bb0ce4a0aa341ce370465527d
Partial-Bug: #1600468

doc/training-guides/associate-guide/01-getting-started.rst

@@ -59,7 +59,7 @@ Release Cycle
 
   - Made of four major stages: Planning, Implementation, Pre-release, Release
 
-.. image:: ../figures/image05.png
+.. image:: ../figures/community-heartbeats.png
 
 *Community Heartbeat*
 
@@ -111,7 +111,7 @@ Conceptual Architecture
 Conceptual Architecture (cont)
 ==============================
 
-.. image:: ../figures/image13.jpg
+.. image:: ../figures/conceptual-arch.jpg
 
 *Conceptual Diagram*
 
@@ -139,7 +139,7 @@ Conceptual Architecture (cont)
 Logical Architecture
 ====================
 
-.. image:: ../figures/openstack-arch-havana-logical-v1.jpg
+.. image:: ../figures/arch-havana-logical-v1.jpg
 
 *Logical diagram*
 
@@ -166,7 +166,7 @@ Dashboard (horizon)
 - Provides an end user and administrator interface to OpenStack services.
 - A modular Django web application
 
-.. image:: ../figures/image10.jpg
+.. image:: ../figures/horizon-essex.jpg
   :width: 75%
 
 .. note::

doc/training-guides/associate-guide/03-using-with-horizon.rst

@@ -72,7 +72,7 @@ Dashboard - Overview
   - Top-level row shows the username that you logged in with
   - Also access Settings or Sign Out of the Web interface
 
-.. image:: ../figures/image14.png
+.. image:: ../figures/horizon-main-dashboard.png
 
 Dashboard - Project tab
 =======================
@@ -169,7 +169,7 @@ Add security group rules (cont)
   - The Dashboard shows the security groups that are available for this
     project.
 
-.. image:: ../figures/image25.png
+.. image:: ../figures/horizon-secgroup-list.png
 
 Add security group rules (cont)
 ===============================
@@ -177,7 +177,7 @@ Add security group rules (cont)
   - Select the default security group and click Edit Rules
   - The Security Group Rules page appears:
 
-.. image:: ../figures/image15.png
+.. image:: ../figures/horizon-secgroup-edit.png
 
 Add keypairs
 ============
@@ -210,14 +210,14 @@ OpenStack Dashboard - Instances
   - Launch an instance from a volume
   - Create instance snapshots
 
-.. image:: ../figures/image00.png
+.. image:: ../figures/horizon-instances.png
 
 OpenStack Dashboard - Actions
 =============================
 
 - Control the state of an instance
 
-.. image:: ../figures/image30.png
+.. image:: ../figures/horizon-actions.png
 
 OpenStack Dashboard - Track Usage
 =================================
@@ -225,7 +225,7 @@ OpenStack Dashboard - Track Usage
 - Use the Dashboard's Overview category to track usage of instances for each
   project.
 
-.. image:: ../figures/image14.png
+.. image:: ../figures/horizon-main-dashboard.png
 
 OpenStack Dashboard - Track Usage (cont)
 ========================================

doc/training-guides/associate-guide/07-associate-network-node.rst

@@ -145,7 +145,7 @@ Typically at least **four** distinct **physical** data center **networks**:
 OpenStack Networking - Connectivity
 ===================================
 
-.. image:: ../figures/image33.png
+.. image:: ../figures/network-connectivity.png
 
 
 OpenStack Networking Concepts
@@ -175,7 +175,7 @@ OpenStack Networking Concepts (cont)
 OpenStack Networking Concepts (cont)
 ====================================
 
-.. image:: ../figures/image49.png
+.. image:: ../figures/network-concept.png
 
 Managing Networks - CLI
 =======================