docs: Add debugging section to process

This idea was formed after noticing that new developers experience
certain difficulty to navigate within the multitude of different
debugging options in the Kernel and while there often is good
documentation for the tools, the developer has to know first that they
exist and where to find them.
Add a general debugging section to the Kernel documentation, as an
easily locatable entry point to other documentation and as a general
guideline for the topic.

Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241028-media_docs_improve_v3-v3-1-edf5c5b3746f@collabora.com