licenses: Add SPDX headers to RST documentation

The documentation files are licensed under CC-BY-SA-4.0, but this has
never been specified explicitly. Add corresponding SPDX headers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/README.rst b/README.rst
index e60d7aec..656fdbfd 100644
--- a/README.rst
+++ b/README.rst
@@ -1,3 +1,5 @@
+.. SPDX-License-Identifier: CC-BY-SA-4.0
+
 .. section-begin-libcamera
 
 ===========