diet (ZECO_0000112) - make def species agnostic

[sjm41]

diet (ZECO_0000112)
Experimental condition where the food of the zebrafish is manipulated in some way.

If this term is to be used by non-ZFIN groups within phenotype and disease model annotations at the Alliance, then the definition needs to become species agnostic. So it could be changed to something simple like "Experimental condition where the food of the organism is manipulated in some way."