[config-ref] normalize file naming by service name

Change-Id: I216ca2daa3410ffc24daba6d7b5e528e114c4008

doc/config-reference/source/database.rst

@@ -4,9 +4,9 @@ Database service
 
 .. toctree::
 
-   database-service/database.rst
+   database/database.rst
-   database-service/rpc.rst
+   database/rpc.rst
-   database-service/logs.rst
+   database/logs.rst
    tables/conf-changes/trove.rst
 
 The Database service provides a scalable and reliable Cloud

doc/config-reference/source/image.rst

@@ -4,11 +4,11 @@ Image service
 
 .. toctree::
 
-   image-service/api.rst
+   image/api.rst
-   image-service/rpc.rst
+   image/rpc.rst
-   image-service/backends.rst
+   image/backends.rst
-   image-service/logs.rst
+   image/logs.rst
-   image-service/sample-configuration-files.rst
+   image/sample-configuration-files.rst
    tables/conf-changes/glance.rst
 
 Compute relies on an external image service to store virtual machine images and

doc/config-reference/source/index.rst

@@ -26,10 +26,10 @@ Contents
    compute.rst
    dashboard.rst
    data-processing-service.rst
-   database-service.rst
+   database.rst
    identity.rst
-   image-service.rst
+   image.rst
-   messaging.rst
+   message.rst
    networking.rst
    object-storage.rst
    orchestration.rst

doc/config-reference/source/message.rst

@@ -5,17 +5,17 @@ Message service
 .. toctree::
    :maxdepth: 1
 
-   messaging/zaqar-conf.rst
+   message/zaqar-conf.rst
-   messaging/zaqar-api.rst
+   message/zaqar-api.rst
-   messaging/zaqar-logging.rst
+   message/zaqar-logging.rst
-   messaging/zaqar-drivers.rst
+   message/zaqar-drivers.rst
-   messaging/zaqar-storage-drivers.rst
+   message/zaqar-storage-drivers.rst
-   messaging/zaqar-transport-drivers.rst
+   message/zaqar-transport-drivers.rst
-   messaging/zaqar-notifications.rst
+   message/zaqar-notifications.rst
-   messaging/zaqar-authentication.rst
+   message/zaqar-authentication.rst
-   messaging/zaqar-pooling.rst
+   message/zaqar-pooling.rst
-   messaging/logs.rst
+   message/logs.rst
-   messaging/zaqar-cache.rst
+   message/zaqar-cache.rst
 
 The Message service is multi-tenant, fast, reliable, and scalable. It allows
 developers to share data between distributed application components performing