slight updates to class names and mutation name

portal/graphql_schema.py

@@ -240,7 +240,7 @@ class Query(graphene.ObjectType):
         return qs.distinct()
 
 
-class DataFileAnnotationMutation(DjangoModelFormMutation):
+class DataFileAnnotationsMutation(DjangoModelFormMutation):
     """Enable the modification of a DataFile
     Makes use of the DataFileForm, so all exposed fields from that form are available"""
 
@@ -332,7 +332,7 @@ class DataFileAttachMutation(graphene.Mutation):
 
 
 class Mutation(graphene.ObjectType):
-    datafile = DataFileAnnotationMutation.Field()
+    datafile_annotations = DataFileAnnotationsMutation.Field()
     dataset = DataSetMutation.Field()
     attach_datafile_by_hash = DataFileAttachMutation.Field()