docs/sphinx: License content with CC-BY-4.0

Creative Commons is a more common license than GPL for documentation purposes.
Switch to using CC-BY-4.0 to explicitly permit re-purposing and remixing of
the content.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Lars Kurth <lars.kurth@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>

COPYING

@@ -47,6 +47,9 @@ various drivers, support functions and header files within Xen-aware
 Linux source trees. In all such cases, license terms are stated at the
 top of the file or in a COPYING file in the same directory.
 
+Sphinx documentation is licensed under CC-BY 4.0.  See
+docs/README.source for more specific information.
+
 In some cases, compatible 3rd party code has been imported into the
 Xen tree, retaining the original license, such as
   - AES-128 3.0

docs/README.source

@@ -0,0 +1,32 @@
+Sphinx documentation:
+
+All source rendered by Sphinx is licensed under CC-BY-4.0.
+
+You are free to:
+  Share:
+    Copy and redistribute the material in any medium or format.
+  Adapt:
+    Remix, transform, and build upon the material for any purpose, even
+    commercially.
+
+Under the following terms:
+  Attribution:
+    You must give appropriate credit, provide a link to the license, and
+    indicate if changes were made. You may do so in any reasonable manner, but
+    not in any way that suggests the licensor endorses you or your use.
+  No additional restrictions:
+    You may not apply legal terms or technological measures that legally
+    restrict others from doing anything the license permits.
+
+See https://creativecommons.org/licenses/by/4.0/ for full details.
+
+This includes:
+  * All ReStructured Text files:          docs/*/*.rst
+  * The Sphinx configuration file:        docs/conf.py
+  * Content in Sphinx-exclusive subdirs:  docs/*-guide/*
+
+
+Other documentation:
+
+There are a variety of text documents in various formats.  These, given no
+explicit license guidance, fall under Xen's default GPL-2.0 license.

docs/admin-guide/index.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Admin Guide
 ===========
 

docs/admin-guide/introduction.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Introduction
 ============
 

docs/admin-guide/microcode-loading.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Microcode Loading
 =================
 

docs/conf.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+# SPDX-License-Identifier: CC-BY-4.0
 #
 # Configuration file for the Sphinx documentation builder.
 #

docs/glossary.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Glossary
 ========
 

docs/guest-guide/index.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Guest documentation
 ===================
 

docs/guest-guide/x86/hypercall-abi.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Hypercall ABI
 =============
 

docs/guest-guide/x86/index.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 x86
 ===
 

docs/hypervisor-guide/code-coverage.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Code Coverage
 =============
 

docs/hypervisor-guide/index.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 Hypervisor documentation
 ========================
 

docs/index.rst

@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-4.0
+
 The Xen Hypervisor documentation
 ================================