This commit updates the "ceph df" output
so that it is current as of October 2020.
-Add correctly formatted `ceph df` output.
-Add explanation of "DIRTY" column.
-(DATA) remains to be defined (1 instance)
-(OMAP) remains to be defined (1 instance)
-USED remains to be defined (1 instance)
-Update prompts in "Checking OSD Status"