Docs: ktap: add code-block type

Fix multiple "code-block::" warnings by adding "none" as the type of
code-block. Mends these warnings:

Documentation/dev-tools/ktap.rst:71: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:120: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:126: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:132: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:139: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:145: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:195: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:208: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.
Documentation/dev-tools/ktap.rst:238: WARNING: Error in "code-block" directive:
1 argument(s) required, 0 supplied.

Fixes: a32fa6b2

 ("Documentation: dev-tools: Add KTAP specification")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rae Moar <rmoar@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Reviewed-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20220131003637.14274-1-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>