docs: add docs for carousel and config-provider (#8)

* docs: add docs for carousel and config-provider

one/docs/demo/carousel/effect.vue

@@ -0,0 +1,67 @@
+<template>
+<article>
+  <section>
+    <h4>Effect type</h4>
+    <veui-radio-group
+      v-model="effect"
+      :items="effects"
+    />
+  </section>
+  <section>
+    <veui-carousel
+      :datasource="items"
+      :effect="effect"
+    />
+  </section>
+</article>
+</template>
+
+<script>
+import { Carousel, RadioGroup } from 'veui'
+
+export default {
+  components: {
+    'veui-carousel': Carousel,
+    'veui-radio-group': RadioGroup
+  },
+  data () {
+    return {
+      items: [
+        {
+          src:
+            'https://ecmb.bdimg.com/public01/one-design/2b77cc4a4c5c906993c0e512f3ddaf03.jpg',
+          alt: 'A cute kitty looking at you with its greenish eyes.',
+          label: 'Cat'
+        },
+        {
+          src:
+            'https://ecmb.bdimg.com/public01/one-design/6fedc62b9221846ce5114c7447622e47.jpeg',
+          alt: 'A common kingfisher flying above river.',
+          label: 'Kingfisher'
+        },
+        {
+          src:
+            'https://ecmb.bdimg.com/public01/one-design/e1b6473c898d9e456452ee79d7533a86.jpeg',
+          alt: 'A white and gray dolphin in blue water.',
+          label: 'Dolphin'
+        }
+      ],
+      effect: 'fade',
+      effects: [
+        { label: 'Fade', value: 'fade' },
+        { label: 'Slide', value: 'slide' }
+      ]
+    }
+  }
+}
+</script>
+
+<style lang="less" scoped docs>
+h4 {
+  margin: 0 0 10px;
+}
+
+section {
+  margin-bottom: 10px;
+}
+</style>