Added 'a11y' and 'source' addons to storybook as well as more stories

stories/FieldNumber.stories.js

@@ -2,13 +2,15 @@ import React from 'react';
 import {useActionState} from './helper';
 import FieldNumber from '../src/components/FieldNumber';
 import {Wrapper} from './ui';
+import {withA11y} from '@storybook/addon-a11y';
 
 export default {
   title: 'FieldNumber',
   component: FieldNumber,
+  decorators: [withA11y],
 };
 
-export const Simple = () => {
+export const Basic = () => {
   const [value, setValue] = useActionState("onChange", 1);
 
   return (