fix: expose composeWithMongooseDiscriminators, other utils to src/index.js

Other Utils -> mergeCustomisationsOptions, DiscriminatorTypeComposer class

Author: mernxl

src/index.js

@@ -1,9 +1,11 @@
 /* @flow */
 
 import { composeWithMongoose } from './composeWithMongoose';
+import { composeWithMongooseDiscriminators } from './composeWithMongooseDiscriminators';
 import GraphQLMongoID from './types/mongoid';
 
 export default composeWithMongoose;
 
 export * from './fieldsConverter';
-export { composeWithMongoose, GraphQLMongoID };
+export * from './discriminators';
+export { composeWithMongoose, composeWithMongooseDiscriminators, GraphQLMongoID };