chore(docz): use category() instead of group

examples/basic/src/components/Alert.doc.jsx

@@ -2,10 +2,9 @@ import React, { Fragment } from 'react'
 import { doc } from 'docz'
 
 import { Alert } from './Alert'
-import { components } from './'
 
 doc('Alert')
-  .group(components)
+  .category('Components')
   .description('This component is used to show alerts')
   .section('Basic usage', () => <Alert>Some message</Alert>)
   .section('Using different kinds', () => (

examples/basic/src/components/Button.doc.jsx

@@ -2,8 +2,7 @@ import React from 'react'
 import { doc } from 'docz'
 
 import { Button } from './Button'
-import { components } from './'
 
 doc('Button')
-  .group(components)
+  .category('Components')
   .section(() => <Button>Click me</Button>)

examples/basic/src/components/index.jsx

@@ -1,6 +1,2 @@
-import { group } from 'docz'
-
 export { Alert } from './Alert'
 export { Button } from './Button'
-
-export const components = group('Components')