add feature_SO_term for feature_truncation and feature_elongation
add feature_SO_term for feature_truncation and feature_elongation

willmclaren/ensembl-variation,dbolser-ebi/ensembl-variation,Ensembl/ensembl-variation,dbolser/ensembl-variation,Ensembl/ensembl-variation,willmclaren/ensembl-variation,Ensembl/ensembl-variation,Ensembl/ensembl-variation,dbolser/ensembl-variation,dbolser/ensembl-variation,dbolser-ebi/ensembl-variation,Ensembl/ensembl-variation,dbolser-ebi/ensembl-variation,willmclaren/ensembl-variation,willmclaren/ensembl-variation,willmclaren/ensembl-variation,dbolser/ensembl-variation