[h5md-user] description attribute

[Felix Höfling]

Hi Pierre and Peter,

I suggest an optional attribute "description" to each data set.  
Descriptive group identifiers are useful, but sometimes not precise  
enough. For example, I would like to have a description like "potential  
energy per particle" attached to the observable group potential_energy.

Are there any objections to this?

Cheers,
Felix