Update Recommendations.md regarding deprecated data name `_diffrn_source.description`

[danielnrainer]

Hiya

In the recommendations, the data name _diffrn_source.description is mentioned. However, this data name has since been deprecated in the core CIF and succeeded by _diffrn_source.device and _diffrn_source.details, the former being enumerated and the only applicable code for electron diffraction would be elect-micro.

I guess the recommendations here in the cif_ed should be adapted to not recommend the use of a deprecated data name. But before changing the recommendation (I've been struggling to come up with a solution I'm happy with), given the explanations here, should the code in _diffrn_source.device then by updated to elect-gun or similar (or this new code added)?

[jamesrhester]

If elect-micro doesn't capture the nature of the source adequately, then a PR to add a new item to the enumerated list in _diffrn_source.device would be appropriate.

[danielnrainer]

Thanks @jamesrhester! I also conferred with Lukas and Brian in the meantime and I will make a PR for cif_core to suggest a tweak to the description of _diffrn_source.device, this is likely sufficient. I'll then later make a corresponding PR here to change recommendations.md.