Add step by step tutorial building a dmr++ sidecar file from a h5/nc4 dataset with

[Mikejmnez]

I think the documentation would greatly benefit by adding step-by-step instructions on how to build dmr++ files from a h5 and/or nc4 dataset with the following options:

1. H5.EnableCF=true and
2. H5.EnableCF=false
3. Explain the difference and emphasis which to use (and why).

From the current state of the documentation it is somewhat unclear how to set these parameters to true or false, how to use a site.conf file to do so, and what a successful result should look like.

We should pick a relatively interesting dataset too