docs: Move licence/copyright from HTML output to rST comments

Our built HTML documentation now has a standard footer which
gives the license for QEMU (and its documentation as a whole).
In almost all pages, we either don't bother to state the
copyright/license for the individual rST sources, or we put
it in an rST comment. There are just three pages which render
copyright or license information into the user-visible HTML.

Quoting a specific (different) license for an individual HTML
page within the manual is confusing. Downgrade the license
and copyright info to a comment within the rST source, bringing
these pages in line with the rest of our documents.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20210722192016.24915-3-peter.maydell@linaro.org

docs/interop/vhost-user-gpu.rst

@@ -2,9 +2,10 @@
 Vhost-user-gpu Protocol
 =======================
 
-:Licence: This work is licensed under the terms of the GNU GPL,
-          version 2 or later. See the COPYING file in the top-level
-          directory.
+..
+  Licence: This work is licensed under the terms of the GNU GPL,
+           version 2 or later. See the COPYING file in the top-level
+           directory.
 
 .. contents:: Table of Contents
 

docs/interop/vhost-user.rst

@@ -3,11 +3,13 @@
 ===================
 Vhost-user Protocol
 ===================
-:Copyright: 2014 Virtual Open Systems Sarl.
-:Copyright: 2019 Intel Corporation
-:Licence: This work is licensed under the terms of the GNU GPL,
-          version 2 or later. See the COPYING file in the top-level
-          directory.
+
+..
+  Copyright 2014 Virtual Open Systems Sarl.
+  Copyright 2019 Intel Corporation
+  Licence: This work is licensed under the terms of the GNU GPL,
+           version 2 or later. See the COPYING file in the top-level
+           directory.
 
 .. contents:: Table of Contents
 

docs/system/generic-loader.rst

 ..
    Copyright (c) 2016, Xilinx Inc.
 
-This work is licensed under the terms of the GNU GPL, version 2 or later.  See
-the COPYING file in the top-level directory.
+   This work is licensed under the terms of the GNU GPL, version 2 or later.  See
+   the COPYING file in the top-level directory.
 
 Generic Loader
 --------------