There is no /add operation for slurm cluster data

[lars-t-hansen]

This is an oversight: slurm cluster data ("cluzter") can only be inserted via kafka subscriptions in the normal data store, or in the timescaledb database. There is no add option that will accept those data (and hence no remote /add API).

[lars-t-hansen]

Actually this is a little more involved. The existing add handlers and the existing add command all accept old-format data. We should probably not fix this, but instead remove / deprecate this functionality and implement a better ingestion API for new-format data (call it "insert" probably). Meanwhile I will just push a documentation fix to clarify this.

[lars-t-hansen]

Doc fixes pushed. Will open a better bug for the rest of the work.