The "Troubleshoot the Block Storage configuration in cinder" had
incorrect config filename, this changes it to cinder.conf
Closes-bug: 1879391
Change-Id: I081a28e617a12a8430f880dd7b0b20cb8d6fb248
This directory is intended to hold any documentation that relates to
how to run or operate Cinder. Previously, this content was in the
admin-guide section of openstack-manuals.