Fix 'server' and 'instance' occurrence in api-ref

some api-ref have sentence like '..for a server instance'
which is inconsistent and confusing as we use server for VM terminology.
I think here 'instance' word is being considered object of server which
is wrong.

We should always mention server only.

part of bp:api-ref-in-rst-pike

Change-Id: I32afe56cfc66b34b76d1f7e1b507d3d5e722e6a1

api-ref/source/os-consoles.inc

@@ -11,7 +11,7 @@ Lists Consoles
 
 .. rest_method:: GET /servers/{server_id}/consoles
 
-Lists all consoles for a server instance.
+Lists all consoles for a server.
 
 Normal response codes: 200
 
@@ -47,7 +47,7 @@ Create Console
 
 .. rest_method:: POST /servers/{server_id}/consoles
 
-Creates a console for a server instance.
+Creates a console for a server.
 
 Normal response codes: 200
 
@@ -71,7 +71,7 @@ Show Console Details
 
 .. rest_method:: GET /servers/{server_id}/consoles/{console_id}
 
-Shows console details for a server instance.
+Shows console details for a server.
 
 Normal response codes: 200
 
@@ -111,7 +111,7 @@ Delete Console
 
 .. rest_method:: DELETE /servers/{server_id}/consoles/{console_id}
 
-Deletes a console for a server instance.
+Deletes a console for a server.
 
 Normal response codes: 202
 
@@ -137,7 +137,7 @@ Show Console Connection Information
 
 .. rest_method:: GET /os-console-auth-tokens/{console_token}
 
-Given the console authentication token for a server instance,
+Given the console authentication token for a server,
 shows the related connection information.
 
 This method used to be available only for the ``rdp-html5`` console type before

api-ref/source/os-virtual-interfaces.inc

@@ -4,7 +4,7 @@
  Servers virtual interfaces (servers, os-virtual-interfaces)
 =============================================================
 
-Lists virtual interfaces for a server instance.
+Lists virtual interfaces for a server.
 
 .. note::
     This API is only implemented for the nova-network service and will result

api-ref/source/os-volume-attachments.inc

@@ -5,7 +5,7 @@
 ===================================================================
 
 Attaches volumes that are created through the volume API to server
-instances. Also, lists volume attachments for a server instance, shows
+instances. Also, lists volume attachments for a server, shows
 details for a volume attachment, and detaches a volume.
 
 List volume attachments for an instance

api-ref/source/server-security-groups.inc

@@ -4,7 +4,7 @@
  Servers Security Groups (servers, os-security-groups)
 ======================================================
 
-Lists Security Groups for a server instance.
+Lists Security Groups for a server.
 
 List Security Groups By Server
 ==============================

api-ref/source/servers-action-console-output.inc

@@ -5,7 +5,7 @@ Show Console Output (os-getConsoleOutput Action)
 
 .. rest_method:: POST /servers/{server_id}/action
 
-Shows console output for a server instance.
+Shows console output for a server.
 
 This API returns the text of the console since boot.
 The content returned may be large. Limit the lines of console