Update FormContext.tsx (#103)

Author: geekrainy

src/FormContext.tsx

@@ -1,16 +1,16 @@
 import * as React from 'react';
 import { ValidateMessages, FormInstance, FieldData, Store } from './interface';
 
-interface Forms {
+export interface Forms {
   [name: string]: FormInstance;
 }
 
-interface FormChangeInfo {
+export interface FormChangeInfo {
   changedFields: FieldData[];
   forms: Forms;
 }
 
-interface FormFinishInfo {
+export interface FormFinishInfo {
   values: Store;
   forms: Forms;
 }