Sphinx emits various warnings all caused by a missing colon before code
block:
WARNING: Block quote ends without a blank line; unexpected unindent.
ERROR: Unexpected indentation.
WARNING: Block quote ends without a blank line; unexpected unindent.
Add the colon, clearing sphinx warnings.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>