ScyllaDB has wide variety of tools and source of information useful for
diagnosing problems. These are scattered all over the place and although
most of these are documented, there is currently no document listing all
the relevant tools and information sources when it comes to diagnosing a
problem.
This patch adds just that: a document listing the different tools and
information sources, with a brief description of how they can help in
diagnosing problems, and a link to the releveant dedicated documentation
pages.
Closes#12503
