This commit uses the new .. zephyr:code-sample-category directive to
categorize code samples across the tree.
Updates existing legacy references to manually defined targets to now
use :zephyr:code-sample-category: role instead.
Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
Describe the samples using code-sample directive in preparation for
upcoming changes to the Zephyr documentation that will be leveraging
the provided description and metadata.
Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
