update docs

Author: kazupon

README.md

@@ -8,7 +8,109 @@
 
 **NOTE:** :warning: This `next` branch is development branch for Vue 3! The stable version is now in [`master`](https://github.com/intlify/vue-i18n-extensions/tree/master) branch!
 
-## Status: WIP ![Test](https://github.com/intlify/vue-i18n-extensions/workflows/Test/badge.svg)
+## Status: Alpha ![Test](https://github.com/intlify/vue-i18n-extensions/workflows/Test/badge.svg)
+
+This library exports the following extensions:
+
+## :star: Features
+- module: `v-t` custom directive compiler module for the following:
+  - `@vue/compiler-core` (`options` at `baseCompile` function)
+  - `@vue/compiler-dom` (`options` at `compile` function)
+  - `@vue/compiler-sfc` (`compilerOptions` at `compileTemplate` function)
+  - `vue-loader` (`compilerOptions` at `options`)
+
+## :cd: Installation
+
+```sh
+$ npm i --save-dev @intlify/vue-i18n-extensions@alpha
+```
+
+## :rocket: Extensions
+
+### module: `v-t` custom directive compiler module
+This module is `v-t` custom directive module for vue compilers. You can specify it.
+
+The following example that use `compile` function of `@vue/compiler-dom`:
+
+```js
+import { compile } from '@vue/compiler-dom'
+import { createI18n } from 'vue-i18n'
+import { defineTransformVT } from '@intlify/vue-i18n-extensions'
+
+const i18n = createI18n({
+  locale: 'ja',
+  messages: {
+    en: {
+      hello: 'hello'
+    },
+    ja: {
+      hello: 'こんにちは'
+    }
+  }
+})
+const transformVT = defineTransformVT(i18n)
+
+const { code } = compile(`<p v-t="'hello'"></p>`, {
+  mode: 'function',
+  hoistStatic: true,
+  prefixIdentifiers: true,
+  directiveTransforms: { t: transformVT }
+})
+console.log(codel)
+/* output -> 'hello'
+  const { createVNode: _createVNode, openBlock: _openBlock, createBlock: _createBlock } = Vue
+
+  const _hoisted_1 = { textContent: "こんにちは" }
+
+  return function render(_ctx, _cache) {
+    return (_openBlock(), _createBlock("p", _hoisted_1))
+  }
+*/
+```
+
+The following configration example of `vue-loader`:
+
+```js
+const { VueLoaderPlugin } = require('vue-loader')
+const { createI18n } = require('vue-i18n')
+const { defineTransformVT } = require('@intlify/vue-i18n-extensions')
+
+const i18n = createI18n({
+  locale: 'ja',
+  messages: {
+    en: {
+      hello: 'hello'
+    },
+    ja: {
+      hello: 'こんにちは'
+    }
+  }
+})
+const transformVT = defineTransformVT(i18n)
+
+module.exports = {
+  module: {
+    // ...
+    rules: [
+      {
+        test: /\.vue$/,
+        use: [
+          {
+            loader: 'vue-loader',
+            options: {
+              compilerOptions: {
+                directiveTransforms: { t: transformVT }
+              }
+            }
+          }
+        ]
+      },
+      // ...
+    ]
+  },
+  plugins: [new VueLoaderPlugin()]
+}
+```
 
 ## :copyright: License