This PR rewrites a section in the Troubleshooting
chapter of the Cephadm Guide. The material that this
section discusses has been covered already in the
Cephadm Guide in the Cephadm Operations chapter.
There's no reason to repeat this information twice,
unless adding technical debt to the documentation
is our goal (which of course it is not, and the
opposite of adding technical debt to the documentation
has been the aim that has guided my work these past
six months).